Api5l part 1 of 2b

Understanding API5LAPI SPEC 5L- 45th EditionForty-fifth Edition, December 2012The Inspector Perspective Reading 1 Part 1/2B22nd April 2016

Charlie Chong/ Fion Zhang

10.2.3.7 Test pieces for the flattening testThe test pieces shall be taken in accordance with ISO 8492 or ASTM A 370, except that the length ofeach test piece shall be 60 mm (2.5 in).Minor surface imperfections may be removed by grinding.

Fion Zhang/Charlie Chong

API5L Mechanical Lab


D W T T

Fion Zhang/Charlie C

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Drop weight tear test (DWTT)

https://www.youtube.com/embed/n5aL6oM7ZAM

10.2.4 Test methods10.2.4.1 Product analysisUnless otherwise agreed upon when ordering, the choice of a suitable physical or chemical method of analysis to determine the product analysis is at the discretion of the manufacturer. In cases of dispute, the analysis shall becarried out by a laboratory approved by the two parties. In these cases, thereference method of analysis shall be agreed upon, where possible, withreference to ISO/TR 9769 or ASTM A751. NOTE ISO/TR 9769 covers a list ofavailable International Standards for chemical analysis, with information onthe application and precision of the various methods.


10.2.4.2 Tensile testThe tensile test shall be carried out in accordance with ISO 6892-1 or ASTM A370. For pipe body tests, the yield strength, the tensile strength, the yieldratio (as appropriate), and the percentage elongation after fracture shall bedetermined. For pipe weld tests, the tensile strength shall be determined. Thepercentage elongation after fracture shall be reported with reference to agauge length of 50 mm (2 in). For test pieces having a gauge length less than50 mm (2 in), the measured elongation after fracture shall be converted to apercentage elongation in 50 mm (2 in) in accordance with ISO 2566- 1 orASTM A370.


Tensile test

Fion Zhang/Charlie Chong http://www.directindustry.com/prod/shanghai-hualong-test-instruments-corporation/product-38790-424621.html

T e n s i l e t e s t

Fion Zhang/Charlie C

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10.2.4.3 CVN impact testThe Charpy test shall be carried out in accordance with ASTM A370 unless ISO 148-1 and the required striker radius (2 mm or 8 mm) are specified in the purchase order.10.2.4.4 Drop-weight tear testThe drop-weight tear test shall be carried out in accordance with API RP 5L3.10.2.4.5 Full section bend testThe bend test shall be carried out in accordance with ISO 8491 or ASTM A370. For each test unit, one full-section test piece of appropriate length shall be bent cold through 90 around a mandrel having a diameter no larger than 12 D.


CVN impact test

Fion Zhang/Charlie Chong http://www.directindustry.com/prod/shanghai-hualong-test-instruments-corporation/product-38790-424621.html

10.2.4.6 Guided-bend testThe guided-bend test shall be carried out in accordance with ISO 7438 or ASTM A370. The mandrel dimension, Agb, expressed in millimetres (inches), shall not be larger than that determined using Equation (5), with the result rounded to the nearest 1 mm (0.1 in):


whereD is the specified outside diameter, expressed in millimetres (inches);t is the specified wall thickness when using full thickness pieces,

expressed in millimetres (inches). It is 19 mm (0.748 in.) when using reduced-thickness test pieces;

is the strain, as given in Table 23;1,15 is the peaking factor.

Both test pieces shall be bent 180 in a jig as shown in Figure 9. One test piece shall have the root of the weld directly in contact with the mandrel; the other test piece shall have the face of the weld directly in contact with the mandrel.


Figure 9 . Jigs for guided-bend test


a) Plunger type Dimensions in millimetres (inches)


Key1 tapped mounting hole2 shoulders, hardened and greased, or hardened rollersB Agb 2t 3,2 mm (0.125 in)ra radius of the mandrel for the guided-bend testrb radius of the die for the guided-bend testa These symbols have been retained on the basis of their long-standing use by API in API 5L and API 5CT[21].b As needed.


Table 23 . Strain values for guided-bend test


Guided-bend test


10.2.4.7 Flattening testThe flattening test shall be carried out in accordance with ISO 8492 or ASTM A370. As shown in Figure 6, one of the two test pieces taken from both end-of-coil locations shall be tested with the weld at the 6 o.clock position or 12o.clock position, whereas the remaining two test pieces shall be tested at the3 o.clock position or 9 o.clock position. Test pieces taken from crop ends atweld stops shall be tested at the 3 o.clock position or 9 o.clock position only.


6 o.clock position or 12 o.clock position

3 o.clock position or 9 o.clock position

Flattening test


Flattening testRing Flattening Test, ASTM A513


Flattening test


10.2.4.8 Hardness testWhen suspected hard spots are detected by visual inspection, hardness tests shall be carried out in accordance with ISO 6506, ISO 6507, ISO 6508 or ASTM A370 using portable hardness test equipment and methods complying with ASTM A956, ASTM A1038 or ASTM E110 respectively depending on themethod used.


10.2.5 Macrographic and metallographic tests10.2.5.1 Except as allowed by 10.2.5.2, the alignment of internal and external seams of SAW and COW pipes [see Figure 4d) and Figure 4e)] shall be verified by macrographic testing.

10.2.5.2 Alternative methods, such as ultrasonic inspection, may be used if agreed, provided that the ability of such equipment to detect misalignment isdemonstrated. If such an alternative method is used, a macrographic testshall be carried out at the beginning of the production of each combination ofspecified outside diameter and specified wall thickness.


Figure 4d) Misalignment of weld beads of SAW pipe


Figure 4 e) Misalignment of weld beads of COW pipe


Key1 misalignment

10.2.5.3 For pipe that is required to be seam-heat-treated (see 8.8.1 or 8.8.2, whichever is applicable), it shall be verified by metallographic testing that the entire HAZ has been appropriately heat treated over the full wall thickness.

For pipe that is not required to be seam-heat-treated (see 8.8.1), it shall be verified by metallographic testing that no untempered martensite remains. In addition, a hardness test and maximum hardness may be agreed.

10.2.5.4 For SAW pipe seams made with tack welds, the melting and coalescence of the tack weld into the final weld seam shall be verified by macrographic testing [See 8.4.2 a)].

Question: As a alternative to metallographic as allowed in 10.2.5.2, how UT could assessed 10.2.5.3 , 10.2.5.3.


10.2.6 Hydrostatic test10.2.6.1 Test pressures for all sizes of SMLS pipe, and for welded pipe with D 457 mm (18.000 in), shall be held for not less than 5 seconds. Test pressures for welded pipe with D > 457 mm (18.000 in) shall be held for not less than 10 seconds.


For threaded-and-coupled pipe, the test shall be applied with the couplings made up power-tight if agreed, except that pipe with D > 323.9 mm(12.375 in) may be tested in the plain-end condition. For threaded pipe furnished with couplings made up handling-tight, the hydrostatic test shall bemade on the pipe in the plain-end, threads-only or coupled condition unless a specific condition is specified in the purchase order.

5/10 Seconds

10.2.6.2 In order to ensure that every length of pipe is tested to the required test pressure, each tester, except those on which only continuous welded pipe is tested, shall be equipped with a recording gauge that can record the test pressure and the test duration for each length of pipe, or shall be equipped with some positive and automatic or interlocking device to prevent pipe from being classified as tested until the test requirements (pressure and duration) have been met. Such records or charts shall be available for examination at the manufacturer's facility by the purchaser's inspector, if applicable.

The test- pressure measuring device shall be calibrated by means of a dead-weight tester, or equivalent, no more than four months prior to each use. At the option of the manufacturer, test pressures that are higher than required may be used.

NOTE In all cases, the specified test pressure represents the gauge pressure value below which the pressure is not permitted to fall during the specified test duration.


10.2.6.3 Test pressures for light-wall threaded pipe shall be as given in Table 24.10.2.6.4 Test pressures for heavy-wall threaded pipe shall be as given in Table 25.


Table 24 . Test pressures for light-wall threaded pipe


Table 24 . Test pressures for light-wall threaded pipe


a Not applicable.

Table 25 . Test pressures for heavy-wall threaded pipe


10.2.6.5 Except as allowed by 10.2.6.6, 10.2.6.7 and the footnotes to Table 26, the hydrostatic test pressure, P, expressed in megapascals (pounds persquare inch), for plain-end pipe shall be determined using Equation (6), withthe results rounded to the nearest 0,1 MPa (10 psi):

whereS is the hoop stress, expressed in megapascals (pounds per square

inch), equal to a percentage of the specified minimum yield strength of the pipe, as given in Table 26;

t is the specified wall thickness, expressed in millimetres (inches);D is the specified outside diameter, expressed in millimetres (inches).


(6)

Table 26 . Percentage of specified minimum yield strength for determination of S


10.2.6.6 If pressure testing involves an end-sealing ram that produces a compressive longitudinal stress, the hydrostatic test pressure, P, expressed inmegapascals (pounds per square inch), may be determined using Equation(7), with the result rounded to the nearest 0,1 MPa (10 psi), provided that therequired test pressure produces a hoop stress in excess of 90 % of thespecified minimum yield strength:


(7)

Where:S is the hoop stress, expressed in megapascals (pounds per square

inch), equal to a percentage of the specified minimum yield strength of the pipe (see Table 26);

PR is the internal pressure on end-sealing ram, expressed in megapascals (pounds per square inch);

AR is the cross-sectional area of end-sealing ram, expressed in square millimetres (square inches);

Ap is the cross-sectional area of pipe wall, expressed in square millimetres (square inches);

AI is the internal cross-sectional area of pipe, expressed in square millimetres (square inches);

D is the specified outside diameter, expressed in millimetres (inches);t is the specified wall thickness, expressed in millimetres (inches).


10.2.6.7 If agreed, the minimum permissible wall thickness, tmin, may be used in place of the specified wall thickness, t, for the determination of the required test pressure (see 10.2.6.5 or 10.2.6.6, whichever is applicable), provided that a hoop stress of at least 95 % of the specified minimum yield trength of thepipe is used.


HydrotestingIn order to ensure that every length of pipe is tested to the required test pressure, each tester, except those on which only continuous welded pipe is tested, shall be equipped with a recording gauge that can record the test pressure and the test duration for each length of pipe, or shall be equipped with some positive and automatic or interlocking device to prevent pipe from being classified as tested until the test requirements (pressure and duration) have been met. Such records or charts shall be available for examination at the manufacturer's facility by the purchaser's inspector, if applicable.


HydrotestingTest pressures for all sizes of SMLS pipe, and for welded pipe with D 457 mm (18.000 in), shall be held for not less than 5 seconds. Test pressures for welded pipe with D > 457 mm (18.000 in) shall be held for not less than 10 seconds.


HydrotestingThe test- ressure measuring device shall be calibrated by means of a dead-weight tester, or equivalent, no more than four months

prior to each use. At the option of the manufacturer, test pressures that are higher than required may be used.


10.2.7 Visual inspection10.2.7.1 Except as allowed by 10.2.7.2, each pipe shall be visually inspected to detect surface defects, with an illuminance of at least 300 lx (28 fc). Suchinspection shall be over the entire external surface and shall cover asmuch of the internal surface as is practical.

NOTE Generally, the entire inside surface of large diameter SAW and COW pipes is visually inspected from inside the pipe.

10.2.7.2 Visual inspection may be replaced by other inspection methods that have a demonstrated capability of detecting surface defects.

10.2.7.3 Visual inspection shall be conducted by personnel whoa) are trained to detect and evaluate surface imperfections;b) have visual acuity that meets the applicable requirements of ISO 11484 or

ASNT SNT-TC-1A or equivalent.


Pipe End Visual Inspection


Visual inspection may be replaced by other inspection methods that have a demonstrated capability of detecting surface defects.


V i s u a l i n s p e c t i o n m a y b e r e p l a c e d b y o t h e r

i n s p e c t i o n m e t h o d s t h a t

h a v e a d e m o n s t r a t e d c a p a b i l i t y o f d e t e c t i n g

s u r f a c e d e f e c t s .

F i o n Z h a n g / C h a r l i e C h o n g

10.2.7.4 The surface of cold-formed welded pipe shall be inspected to detect geometric deviations in the contour of the pipe. If this inspection fails todisclose mechanical damage as the cause of the irregular surface, butindicates that the irregular surface can be attributed to a hard spot, thedimensions of the area, and if necessary its hardness, shall be determined.The choice of the test method for hardness testing is at the option of themanufacturer. If the dimensions and hardness exceed the acceptancecriteria given in 9.10.6, the hard spot shall be removed in accordance withprocedures specified in 9.10.7 and Annex C.

Comments:Visual inspection could detect1. Undercut2. Arc burn3. Dent4. Geometric deviation5. Weld reinforcement6. Flash7. Weld defect open to surface


10.2.8 Dimensional testing10.2.8.1 The diameter of pipes shall be measured at least once per 4 hours per operating shift to verify conformance to the diameter tolerances (seeTable 10). Unless a method is specified in the purchase order, diametermeasurements shall be made with a circumferential tape, or appropriate usesof micrometer, ring gauge, snap gauge, caliper, ovality gauge, coordinatemeasuring machine, or optical measuring device. Unless otherwise agreed,for D508 mm (20.000 in.), measurements made by circumferential tape shall govern in case of dispute.


Circumferential Tape

Fion Zhang/Charlie Chong http://tide-tools.en.made-in-china.com/product/UelEdFJKrvRs/China-Circumferential-Measuring-Tape.html#

NOTE 1 Ring gauges used to measure pipe diameter are usually manufactured to specified dimensions for each pipe size from dimensionallystable material such as steel, aluminium or other approved material, and shallbe of rigid construction but sufficiently light to permit manipulation by oneinspector. The ring gauge design usually incorporates handles to allow theinspector to position the gauge accurately and safely within or over the pipe.

The diameter of internal ring gauges is usually 3,2 mm (0.125 in) less thanthe nominal internal diameter of the pipe. External ring gauges usually have abore diameter not exceeding the sum of the specified outside diameter of thepipe plus the allowable diameter tolerance. For inspection of submerged arcwelded pipe, ring gauges can be slotted or notched to permit passage of thegauge over the weld reinforcement. It is necessary that the pipe permit thepassage of the ring gauge within (internal) or over (external) each end of thepipe for a minimum distance of 100 mm (4.0 in).

NOTE 2 Coordinate measuring machines are mechanical systems designed to track a mobile measuring probe to determine the coordinates of points on a work surface.


Plug Gauge


10.2.8.2 The out-of-roundness of pipes shall be determined at least once per 4 hours per operating shift. Except as allowed by 10.2.8.3, the out-of-roundness shall be determined as the difference between the largest outsidediameter and the smallest outside diameter, as measured in the same cross-sectional plane.

NOTE Out-of-roundness measurements taken in stacks are invalid due to the elastic deformations caused by forces exerted by pipes adjacent to those being measured.


10.2.8.3 If agreed, for expanded pipe with D 219,1 mm (8.625 in) and for non-expanded pipe, inside diameter measurements shall be used to determine conformance with the diameter tolerances. The out- of- roundness may be determined as the difference between the largest inside diameter and the smallest inside diameter, as measured in the same cross-sectional plane.

10.2.8.4 For SAW and COW pipe, the greatest deviation of flat spots or peaks from the normal contour of the pipe at the weld at a pipe end shall bemeasured with respect to a template that is oriented transverse to the pipeaxis and has a length of 0,25 D ( D) or 200 mm (8.0 in), whichever is the lesser.


10.2.8.5 Each length of pipe shall be measured for conformance to the specified wall thickness requirements. The wall thickness at any location shallbe within the tolerances specified in Table 11, except that the weld areashall not be limited by the plus tolerance.

Wall thickness measurements shall be made with a mechanical calliper or with a properly calibrated non- destructive inspection device of appropriate accuracy. In case of dispute, the measurement determined by use of the mechanical calliper shall govern.

The mechanical calliper shall be fitted with contact pins. The end of the pincontacting the inside surface of the pipe shall be rounded to a maximumradius of 38,1 mm (1.50 in) for pipe of size 168,3 mm (6.625 in) or larger, andup to a radius of D/4 for pipe smaller than size 168,3 mm (6.625 in) with aminimum radius of 3,2 mm (0.125 in). The end of the pin contacting theoutside surface of the pipe shall be either flat or rounded to a minimum radiusof 31,2 mm (1.25 in).


10.2.8.6 For threaded-and-coupled pipe, the length shall be measured to the outer face of the coupling. The length of threaded-and-coupled pipe may bedetermined before the couplings are attached, provided the proper allowanceis made for the length of the couplings.

10.2.8.7 For the verification of conformance with the dimensional and geometrical requirements specified in 9.11 to 9.13, suitable methods shall be used. Unless particular methods are specified in the purchase order, the methods used shall be at the discretion of the manufacturer.


Threaded-and-coupled Pipe API5B


Dimensional Checks Callipered Diameter/Ovality


Dimensional Checks- String Straightness


Dimensional Checks- Internal Diameter


Dimensional Checks Bevel Angle


Dimensional Checks - Root face


Dimensional Checks End Thickness


Dimensional Checks- End Squareness


D i m e n s i o n a l C h e c k s - O v a l i t y

F i o n Z h a n g / C h a r l i e C h o n g

10.2.9 WeighingFor pipe with D 141,3 mm (5.563 in), the lengths of pipe shall be weighed individually, except that for welded jointers it shall be permissible to weigh theindividual lengths comprising the jointer or the jointer itself.

For pipe with D < 141,3 mm (5.563 in), the lengths of pipe shall be weighed either individually or in a convenient group of pipes selected by the manufacturer. Threaded- end-coupled pipe shall be weighed either:

a) with the couplings screwed on but without thread protectors, except for order items with a mass of 18 tonnes (20 tons) or more for which proper allowance shall be made for the weight of the thread protectors, or

b) before the couplings are attached, provided that allowance is made for the weight of the couplings.


10.2.10 Non-destructive inspectionNon-destructive inspection shall be in accordance with Annex E.


Manual UT Precalibration


Online Automatic UT Checks


10.2.11 ReprocessingIf any mechanical property test result for a test unit of pipe fails to conform to the applicable requirements, the manufacturer may elect to:

1. heat treat the test unit of pipe in accordance with the requirements of Table 3, consider it a new test unit,

2. test it in accordance with all requirements of 10.2.12 and 10.2.4 that areapplicable to the order item, and proceed in accordance with theapplicable requirements of this Standard.

Note: no mechanical strain strengthening

After one reprocessing heat treatment, any additional reprocessing heat treatment shall be subject to agreement with the purchaser.

For non-heat treated pipe, any reprocessing heat treatment shall be subject to agreement with the purchaser.

For heat treated pipe, any reprocessing with a different type of heat treatment (see Table 3) shall be subject to agreement with the purchaser.


10.2.12 Retesting10.2.12.1 Recheck analysesIf the product analyses of both samples representing the heat fail to conform to the specified requirements, at the manufacturer's option either the heatshall be rejected or the remainder of the heat shall be tested individually forconformance to the specified requirements.

If the product analysis of only one of the samples representing the heat fails to conform to the specified requirements, at the manufacturer's option, either the heat shall be rejected or two recheck analyses shall be made using twoadditional samples from the heat. If both recheck analyses conform to the specified requirements, the heat shall be accepted, except for the pipe, plate, or coil from which the initial sample that failed was taken.

If one or both recheck analyses fail to conform to the specified requirements, at the manufacturer's option either the heat shall be rejected or the remainder of the heat shall be tested individually for conformance to the specified requirements. For such individual testing, analyses for only the rejecting element or elements need be determined. Samples for recheck analyses shall be taken in the same location as specified for product analyses samples.


Question:What is the initial sampling size of product analysis & ladle analysis?


10.2.12.2 Tensile retestsTensile retest provisions are as follows.a) For all PSL 1 products, PSL 2 products with R, N, and Q delivery conditions, and PSL 2 products with M delivery conditions of grades less thanL450 or X65, (see Tables 2 and 3). If the tensile test specimen representingthe test unit of pipe fails to conform to the specified requirements, themanufacturer may elect to retest two additional lengths from the same testunit.

If both retested specimens conform to the specified requirements, all thelengths in the test unit shall be accepted, except the length from which theinitial specimen was taken.

If one or both of the retested specimens fail to conform to the specified requirements, the manufacturer may elect to individually test the remaining lengths in the test unit. Specimens for retest shall be taken in the same manner as the specimen that failed to meet the minimum requirements. If applicable, reprocessing shall be as defined in 10.2.11.


b) For PSL 2 products with M delivery conditions of grades L450 or X65, or greater (see Table 3). If the tensile specimen representing the test unit fails toconform to the specified requirements, the manufacturer may elect to retesttwo additional lengths from the same test unit.

Specimens for retest shall be taken in the same manner as the original specimen that failed to meet the minimum requirements but should be from two different mother coils or plates, as applicable.

If one or both of the retested specimens fail to conform to the specified requirements, the manufacturer may elect to individually test the remaininglengths in the test unit.

If both retest specimens conform to the specified requirements, the test unit shall be accepted except the lengths from the mother coil or plate from which the initial specimen was taken. These lengths shall have one of the following dispositions:


1) all pipes shall be rejected, or2) each pipe in the test unit shall be tested with the pipe with satisfactory test results accepted, or3) provided individual pipe traceability to mother coil/plate location, the manufacturer shall test additional lengths adjacent to (before, after andbeside, as applicable) the initial failure within the mother coil or plateconsidering adjacent daughter coil(s) or plate(s) as applicable. Pipe testingshall continue until satisfactory results surround the non-conforming section ofthe mother coil/plate. The pipes from the non-conforming section of mothercoil/plate shall be rejected and the remainder of the pipe from the test unitaccepted. If applicable, reprocessing shall be defined as in 10.2.11.


4.37mother coilhot-rolled coil of steel processed from a single reheated slab which is used to produce one or more pieces of pipe

4.14daughter coilportion of steel removed via slitting, cutting or shearing from the mother coil which is used to produce oneor more pieces of pipe


More ReadingTMCP


10.2.12.3 Flattening retestsFlattening retest provisions are as follows:a) Non-expanded electric welded pipe in grades higher than L175 or A25 and non-expanded laser welded pipe smaller than 323,9 mm (12.750 in) producedin single lengths: The manufacturer may elect to retest any failed end until therequirements are met, providing the finished pipe is not less than 80% of itslength after initial cropping.


b) Non-expanded electric welded pipe in grades higher than L175 or A25 and non-expanded laser welded pipe smaller than 323,9 mm (12.750 in) producedin multiple lengths: Where one or more of the flattening tests fail to conform tothe specified requirements, the manufacturer may retest the pipe end aftercropping the defective pipe end. Alternatively the manufacturer may reject thedefective pipe(s) and retest the adjacent end of the next pipe. The retest shallconsist of two specimens, one tested with the seam weld at 0o and one tested with the seam weld at 90o.

If the retest fails to conform to the specified requirements, the manufacturer may either reject the pipes produced from the affected multiple length or retest each end of each remaining individual length produced from the coil with the weld alternatively at 0o and 90o. If the retest conforms to the specified requirements, the remaining portion of the multiple lengths shall be accepted.


c) Cold-expanded electric welded pipe in grades higher than L175 or A25, all welded Grade L175 or A25 in sizes 60,3 mm (2.875 in) and larger; and cold-expanded laser welded pipe smaller than size 323,9 mm (12.750 in):

The manufacturer may elect to retest one end of each of two additional lengths of the same test unit. If both retests are acceptable, all lengths in the test unit shall be accepted, except the original failed length. If one or both retests fail, the manufacturer may elect to repeat the test on specimens cut from one end of each of the remaining individual lengths in the test unit. If applicable, reprocessing shall be as defined in 10.2.11.

Comments:Only 1 retest with penalty is allowed, if fail, all to be tested or reheat.


10.2.12.4 Bend retestsIf the specimen fails to conform to the specified requirements, the manufacturer may elect to make retests on specimens cut from two additionallengths from the same test unit. If all retest specimens conform to thespecified requirements, all the lengths in the test unit shall be accepted,except the length from which the initial specimen was taken. If one or more ofthe retest specimens fail to conform to the specified requirements, themanufacturer may elect to repeat the test on specimens cut from theindividual lengths remaining in the test unit. If applicable, reprocessing shallbe as defined in 10.2.11.



10.2.12.5 Guided-bend retestsIf one or both of the guided-bend specimens fail to conform to the specified requirements, the manufacturer may elect to repeat the tests on specimenscut from two additional lengths of pipe from the same test unit. If suchspecimens conform to the specified requirements, all lengths in the test unitshall be accepted, except the length initially selected for test. If any of theretested specimens fail to pass the specified requirements, the manufacturermay elect to test specimens cut from individual lengths remaining in the testunit.

The manufacturer may also elect to retest any length that has failed to pass the test by cropping back and cutting two additional specimens from the sameend.

If the requirements of the original test are met by both of these additionaltests, that length shall be acceptable. No further cropping and retesting ispermitted. Specimens for retest shall be taken in the same manner asspecified in Tables 19 and 20 and 10.2.3.6. If applicable, reprocessing shall be as defined in 10.2.11.


10.2.12.6 Charpy retestsIn the event that a set of Charpy test specimens fail to meet the acceptance criteria, the manufacturer may elect to replace the test unit of materialinvolved or alternatively to test two more lengths from that test unit. If both ofthe new tests meet the acceptance criteria, then all pipe in that test unit, withthe exception of the original selected length, shall be considered to meet therequirement. Failure of either of the two additional tests shall require testing ofeach length in the test unit for acceptance. If applicable, reprocessing shall beas defined in 10.2.11.



10.2.12.7 Hardness retestsIf the hardness test specimen representing a test unit of pipe fails to conform to the specified requirements, the manufacturer may elect to retest twoadditional lengths from the same test unit. If both retested specimens conformto the specified requirements, all the lengths in a test unit shall be accepted,except the length from which the initial specimen was taken. If one or both ofthe retested specimens fail to conform to the specified requirements, themanufacturer may elect to individually test the remaining lengths in the testunit. Specimens for retest shall be taken in the same manner as the specimenthat failed to meet the minimum requirements (see H.7 or J.8, as applicable).If applicable, reprocessing shall be as defined in 10.2.11.



10.2.12.8 DWT retestsIn the event that a set of DWT test specimens fail to meet the acceptance criteria, the manufacturer may elect to replace the test unit of materialinvolved or alternatively to test two more lengths from that test unit. If both ofthe new tests meet the acceptance criteria, then all pipe in that test unit, withthe exception of the original selected length, shall be accepted. Failure ofeither of the two additional tests shall require testing of each length in the testunit for acceptance. Specimens for retest shall be taken in the same manneras the specimen that failed to meet the minimum requirements (see 10.2.3). Ifapplicable, reprocessing shall be as defined in 10.2.11.



11. Marking


11 Marking11.1 General11.1.1 Pipe and pipe couplings manufactured in accordance with this Standard shall be marked by the manufacturer in the same sequence as they appear in 11.2.1 a) to j) as applicable.

NOTE While the required markings are generally applied in a single straightline, the markings are permitted to wrap around on to multiple lines provided the sequence of information is maintained as read from left to right and from top to bottom.

1.1.2 The required markings on couplings shall be die-stamped or, if agreed, paint-stencilled.


11.1.3 If the purchase order requires API Spec 5L pipe to be supplied, markings identifying Spec 5L pipe shall be required.

11.1.4 Additional markings, as desired by the manufacturer or as specified in the purchase order, may be applied but shall not interrupt the sequence of therequired markings as they appear in 11.2.1 a) to j) as applicable. Suchadditional markings shall be located after the end of the required markingsequence or as a separate marking at some other location on the pipe.


11.2 Pipe markings11.2.1 Pipe markings shall include the following information sequentially, as

applicable:a) name or mark of the manufacturer of the pipe (X);b) "API Spec 5L" shall be marked when the product is in complete

compliance with this standard, appropriate annexes and this section. Products in compliance with multiple compatible standards may be marked with the name of each standard;

c) specified outside diameter;d) specified wall thickness;e) pipe steel grade (steel name) (see Table 1, Table H.1 or Table J.1,

whichever is applicable) and if agreed, both corresponding SI and USC steel grades may be marked on the pipe with the corresponding steel grade marked immediately after the order item steel grade;


f) product specification level designation followed by the letter G if Annex G is applicable (see G.5.1);

g) type of pipe (see Table 2);h) mark of the customer's inspection representative (Y), if applicable;i) an identification number (Z), which permits the correlation of the product or

delivery unit (e.g bundled pipe) with the related inspection document, if applicable;

j) if the specified hydrostatic test pressure is higher than the test pressure specified in Tables 24 or 25 as applicable, or exceeding the pressures stated in note a, b, or c of Table 26 if applicable, the word TESTED shall be marked at the end of the marking immediately followed by the specified test pressure in psi if ordered to USC units or MPa if ordered to SI units.


EXAMPLE 1 (For SI units) X API Spec 5L 508 12,7 L360M PSL 2 SAWL Y Z

EXAMPLE 2 (For USC units) X API Spec 5L 20 0.500 X52M PSL 2 SAWL Y Z

inspection representative (Y)identification number (Z)

EXAMPLE 3 If pipe also meets the requirements of compatible standard ABC. (For SI units) X API Spec 5L/ABC 508 12,7 L360M PSL 2 SAWL Y ZEXAMPLE 4 If pipe also meets the requirements of compatible standard ABC. (For USC units) X API Spec 5L/ABC 20 0.500 X52M PSL 2 SAWL Y Z EXAMPLE 5 If hydrotest pressure differs from the standard pressure. (For SI units tested to 17,5 MPa) X API Spec 5L 508 12,7 L360M PSL 2 SAWL Y Z TESTED 17,5EXAMPLE 6 If hydrotest pressure differs from the standard pressure. For USC units tested to 2540 psi) X API Spec 5L 20 0.500 X52M PSL 2 SAWL Y Z TESTED2540


EXAMPLE 3 If pipe also meets the requirements of compatible standard ABC.(For SI units) X API Spec 5L/ABC 508 12,7 L360M PSL 2 SAWL Y Z

ABC = ASTM A333 Gr6 (say)

EXAMPLE 4 If pipe also meets the requirements of compatible standard ABC.(For USC units) X API Spec 5L/ABC 20 0.500 X52M PSL 2 SAWL Y Z

ABC = ASTM A333 Gr6 (say)

EXAMPLE 5 If hydrotest pressure differs from the standard pressure. (For SI units tested to 17,5 MPa) X API Spec 5L 508 12,7 L360M PSL 2 SAWL Y Z TESTED 17,5EXAMPLE 6 If hydrotest pressure differs from the standard pressure. For USC units tested to 2540 psi) X API Spec 5L 20 0.500 X52M PSL 2 SAWL Y Z TESTED2540


EXAMPLE 5 If hydrotest pressure differs from the standard pressure. (For SIunits tested to 17,5 MPa) X API Spec 5L 508 12,7 L360M PSL 2 SAWL Y Z TESTED 17,5

EXAMPLE 6 If hydrotest pressure differs from the standard pressure. ForUSC units tested to 2540 psi) X API Spec 5L 20 0.500 X52M PSL 2 SAWL YZ TESTED2540


EXAMPLE 7 For USC units with both corresponding steel grades marked and application of Annex G indicated X API Spec 5L 20 0.500 X52M L360M PSL2G SAWL Y Z

EXAMPLE 8 For SI units with both corresponding steel grades marked and application of Annex G indicated X API Spec 5L 508 12,7 L360M X52M PSL2G SAWL Y Z

OTE For specified outside diameter markings in USC units, it is not necessary to include the ending zero digits to the right of the decimal sign.


Markings



X API Spec 5L/ ASTM A333Gr6 508 12,7 L360M X52MPSL2G SAWL Y Z

API5L Other standard Outside Diameter Thickness

PSL2 with AnnexG

SAW Longitudinal welding

Inspection mark

Manufacturertraceability

Grade L360TMCP

X52 TMCP

11.2.2 Except as allowed by 11.2.3 and 11.2.4, the required markings shall be applied durably and legibly, as follows:a) For pipe with D 48,3 mm (1.900 in), the markings shall be in one or more of the following locations:1) on a tag fixed to the bundle,2) on the straps or banding clips used to tie the bundle,3) on one end of each pipe,4) continuous along the length;b) For pipe with D 48,3 mm (1.900 in), unless a specific surface is specified in the purchase order, themarkings shall be1) on the outside surface of the pipe, in the sequence listed in 11.2.1, starting at a point between450 mm and 760 mm (1.5 ft and 2.5 ft) from one of the pipe ends, or2) on the inside surface of the pipe, starting at a point at least 150 mm (6.0 in) from one of the pipeends;


Remember the Common Steel GradesA, B42, 4652, 5660, 6570, 80, 90, 100, 120


Common API5LSteel GradesA, B42, 4652, 5660, 6570, 80, 90, 100, 120


11.2.3 If agreed, low-stress die-stamping or vibro-etching on the pipe surface may be used, subject to the following limitations.

a) Such marks shall be on the pipe bevel face or within 150 mm (6.0 in) of one of the pipe ends.

b) Such marks shall be at least 25 mm (1.0 in) from any weld.c) Cold die-stamping [at temperatures < 100 C (210 F)] of plate, coil or pipe

not subsequently heat treated shall be done only if rounded or blunt dies are used.

d) Unless otherwise agreed and specified on the purchase order, cold die stamping shall not be used on all pipe with a specified wall thickness of 4,0 mm (0.156 in) or less and all pipe of grade higher than L175 or A25 not subsequently heat treated.

Keywords:Low-stress die-stamping or vibro-etchingCold die-stamping


Low-stress die-stamping or vibro-etchingCold die-stamping


11.2.4 For pipe intended for subsequent coating, if agreed, marking may be done at the coater's facility rather than at the pipe mill. In such cases,traceability shall be ensured, e.g. by application of a unique number (byindividual pipe or heat of steel).

11.2.5 If a temporary protective coating (see 12.1.2) is applied, the markings shall be legible after such coating.


11.2.6 In addition to the markings specified in 11.2.1, the pipe length shall be marked as follows, in metres to two decimal places (feet to tenths of a foot) or, if greed, in a different format.

a) For pipe with D 48,3 mm (1.900 in), the total length of pipe in the bundle shall be marked on a tag, strap or banding clip attached to the bundle.

b) Unless a specific surface is specified on the purchase order for pipe with D > 48,3 mm (1.900 in), the individual pipe length (as measured on the finished pipe) shall be marked1) at a convenient location on the outside surface of the pipe, or2) at a convenient location on the inside surface of the pipe.

c) For pipe furnished with couplings, the length as measured to the outer face of the coupling shall be marked.


11.2.7 If agreed, the manufacturer shall apply a daub of paint, approximately 50 mm (2 in) in diameter, on the inside surface of each length of pipe. Thepaint colour shall be as given in Table 27 if the pipe grade is applicable; for allother grades, the paint colour shall be as specified in the purchase order.

Table 27 . Paint colour


11.3 Coupling markingsAll couplings in sizes 60,3 mm (2.375 in) and larger shall be identified with the manufacturers name or mark together with API Spec 5L.

11.4 Marking of pipe to multiple grades11.4.1 Marking of pipe to multiple grades is permitted only by agreement between the purchaser and the manufacturer within the following limits:a) Pipe may have multiple markings within the following grade ranges:

1) L290 (X42);2) > L290 (X42) to < L415 (X60);

b) for L415 (X60) & above, multiple grade markings are not allowed;c) Pipe shall be marked to only one PSL level.


for L415 (X60) & above, multiple grade markings are not allowed;

X60


API

11.4.2 The manufacturer is responsible for ensuring that the pipe conforms to all requirements of each of the certified grades. This allows pipe to be used as any of the grades individually.

11.4.3 If pipe is marked to multiple grades, a single inspection document shall be issued referencing the grade combination as marked on the pipe. The inspection document may contain a specific statement that pipe conforms to each grade individually.

11.4.4 After delivery of the pipe, no re-marking or re-certification of the pipe to a different grade or different PSL level (PSL 1 to PSL 2) shall be permitted.


After delivery of the pipe, no re-marking or re-certification of the pipe to a different grade or different PSL level (PSL 1 to PSL 2) shall be permitted.


11.5 Thread identification and certification11.5.1 At the manufacturers option, threaded-end pipe may be identified by stamping or stenciling the pipe adjacent to the threaded ends, with themanufacturers name or mark, API Spec 5B (to indicate the applicablethreading specification), the specified outside diameter of the pipe and the letters LP (to indicate the type of thread).

The thread marking may be applied to products that do or do not bear the APImonogram.

EXAMPLE Size 168,3 mm (6.625 in) threaded-end pipe is marked as follows, using the value that is appropriate for the pipe outside diameter specified onthe purchase order:

(for USC units) X API Spec 5B 6.625 LP or

(for SI units) X API Spec 5B 168,3 LP


11.5.2 The use of the letters API Spec 5B as provided by 11.5.1 shall constitute a certification by the manufacturer that the threads so markedcomply with the requirements in API Spec 5B but should not be construed bythe purchaser as a representation that the product so marked is, in its entirety,in accordance with any API Specification. Manufacturers who use the letters API Spec 5B for thread identification are required to have access to properly certified API master pipe gauges per API Spec 5B.


11.6 Pipe processor markingsPipe heat treated by a processor other that the original pipe manufacturer shall be marked as stipulated in the applicable sub-clauses of Clause 11. Theprocessor shall remove any marking that does not indicate the new conditionof the product as a result of heat treating (such as prior grade identity andoriginal pipe manufacturers name or logo). If a processor is subcontracted bythe pipe manufacturer and performs operations that unavoidably remove orobliterate the marking, the subcontractor may reapply the marking providedthe reapplication is controlled by the pipe manufacturer.


Stenciling of pipe number at bevel face in progress.


Pipe End Internal Traceability


12. Coatings and thread protectors


12 Coatings and thread protectors12.1 Coatings and linings12.1.1 Except as allowed by 12.1.2 to 12.1.4, pipe shall be delivered bare (not coated).12.1.2 If agreed, pipe shall be delivered with a temporary external coating to provide protection from rusting in storage and transit. Such coating shall be hard to the touch and smooth, without excessive sags.12.1.3 If agreed, pipe shall be delivered with a special coating.12.1.4 If agreed, pipe shall be delivered with a lining.


12.2 Thread protectors12.2.1 For threaded pipe with D < 60,3 mm (2.375 in), the thread protectors shall be suitable fabric wrappings or shall be suitable metal, fibre or plastic protectors.12.2.2 For threaded pipe with D 60,3 mm (2.375 in), the thread protectors shall be of such design, material and mechanical strength as to protect the thread and pipe end from damage under normal handling and transportation conditions.12.2.3 Thread protectors shall cover the full length of the thread on the pipe, and shall exclude water and dirt from the thread during transportation and the period of normal storage, which is considered to be approximately one year.12.2.4 The thread forms in thread protectors shall be such that they do not damage the pipe threads.12.2.5 Protector material shall contain no compounds that are capable of causing corrosion or promoting adherence of the protectors to the threads, and shall be suitable for service at temperatures of - 45 C to + 65 C (-50 F to +150 F).


13. Retention of Records


13 Retention of recordsRecords of the following inspections, if applicable, shall be retained by the manufacturer and shall be made available to the purchaser, upon request, for a period of three years after the date of purchase from the manufacturer:a) heat and product analyses;b) tensile tests;c) guided-bend tests;d) CVN tests;e) DWT tests;f) hydrostatic-tester recorder charts or electronic methods of record storage;g) radiographic images for pipe inspection;h) non-destructive inspection by other methods where applicable;


i) qualifications of non-destructive inspection personnel;j) radiographic images for jointer welds;k) repair welding procedure tests;l) records of any other test as specified in the annexes or the purchase order, including all welding procedure specifications (WPS) and welding-procedure qualification test records (WPQT/PQR) (see Annex A and Annex D).


14. Pipe Loading


14 Pipe loadingIf the manufacturer is responsible for the shipment of pipe, the manufacturer shall prepare and follow loading diagrams that detail how the pipe is to bearranged, protected and secured on trucks, railcars, barges or ocean-goingvessels, whichever is applicable. The loading shall be designed to prevent end damage, abrasion, peening and fatigue cracking. The loading shall comply with any rules, codes, standards or recommended practices which are applicable.

NOTE For additional information refer to API RP 5L1 [18] and API RP 5LW [19].


Storage for Delivery


API5L1


API5LW


More Reading


Ductile Fracture Propagation In Gas Pipelines


Ductile Fracture Propagation In Gas PipelinesINTRODUCTIONDesign of gas transportation line needs an optimal compromise between the choice of the operating pressure, linepipe geometry (diameter and thickness)and the steel mechanical properties (tensile and toughness characteristics).The wide variety of the possible solutions requires the development ofspecific tools, able to estimate the safety margin with respect to the eventsresponsible of structural failure. The initiation and propagation of a ductile orbrittle longitudinal crack is one of the most serious events. As a matter of fact,the crack can affect a long part of the line, thus causing a long and costly gasdelivery service breakdown. The fracture propagation control is therefore anextremely important aspect of gas transmission design. The main philosophyfollowed by the gas companies is to avoid brittle fracture initiation, ensuringthat the operating pipeline temperature is higher than the steel ductile-brittletransition temperature, and control the ductile fracture propagation, ensuringthat the linepipe steel has the capacity to absorb sufficient energy to arrest afast propagating ductile crack. This paper deals with the problem of theductile fracture propagation control, and describes how the full scale burst test is an useful and (sometimes) essential tool to manage the matter.


http://www.gruppofrattura.it/pdf/volumi_igf/Case%20histories%20in%20integrity%20and%20failures%20in%20industry/7%20-%20Process%20engineering%20and%20petrolchemical/The%20full%20scale%20burst%20test%20approach%20to%20evaluate%20the%20resistance%20to%20ductile%20fracture.pdf

The Ductile Fracture Propagation In Gas PipellneStarting from crack or defect long enough, the fracture can propagate along thepipeline, in a ductile way if the temperature is above the transition temperature ofthe linepipe steel. ln practice after the burst, decompression waves at variouspressure levels propagate in the gas away from the crack tip. In steady statepropagation conditions, the crack runs at constant speed corresponding to a definite pressure level and steel toughness; if the steel toughness is higher, the fracture speed will decrease to a lower pressure level, and new steady state propagation conditions will be reached. If the steel toughness is high enough, the fracture will continuously slow, turn in a spiral direction and arrest at last.

When gases with heavy components (named "rich gases") are used, the fracture control required significantly higher levels of fracture propagation resistance than for pipeline carrying pure methane. This is because the rich gas decompresses more slowly and so the driving force acting at the crack tip remains high.


To limit the line length interested by crack propagation: the use of gas pipeline steels having appropriate toughness is recommended

to increase the capability of crack arrest. An alternative measure can be the use of external mechanical devices (i.e.

"crack arrestors") that locally increase the pipe fracture resistance.

If the first solution is not practical, because of technological and/or economicallimits, the use of crack stopper devices can be taken into account.


The Ductile Fracture Propagation In Gas Pipellne

Fion Zhang/Charlie Chong http://folk.ntnu.no/zhiliang/?page_id=322

Fion Zhang/Charlie Chong http://www.scad.ugent.be/journal/2011/SCAD_2011_2_2_296.pdf

Figure 1: Inserting high toughness pipe as integral crack arrestor


Figure 2: Heavy wall pipe inserts


Figure 3: Composite crack arrestor used in the Demopipe project


Figure 4: Examples of different external crack arrestors


Figure 6: Classification of steel sleeve crack arrestors


Figure 7: ClockSpring crack arrestor (1: composite coil, 2: adhesive and 3: filler)


Figure 5: Cast iron clamps as crack arrestor [11]

The Ductile Fracture Propagation In Gas Pipellne


The Ductile Fracture Propagation Only In Gas PipellneA sudden rupture, flaw or hole in a pressurized containment or structure will lead to an outflow of the contents and a rapidly falling loading or driving force on the stress concentrators caused by the flaw or hole. If the initial pressure is high enough and the flaw is long or severe enough, a fracture will rapidly propagate in the structure; a so-called running fracture. For steel materials operating above the ductile-to-brittle transition temperature, the velocity of this running fracture is determined by pressure at the proximity of the tip of the moving fracture. This pressure is again determined by the speed of sound in the pressurizing medium. That is, the speed of the fracture is determined by the speed of the depressurization wave moving away from the tip of the propagating fracture.If the pressurization wave moves faster than the fracture, the pressure at the crack tips will eventually be below what is needed to drive the fracture forward, and the fracture will stop (arrest). However, if the depressurization speed of the medium at the pressure close to the crack tip is lower than the velocity of the fracture, the fracture will continue to propagate until e.g. some mechanical hindrance (crack arrestor) increases the local fracture resistance. This race between the depressurization wave and the fracture, we call the fracture race and is illustrated in the figure below.

Fion Zhang/Charlie Chong http://bigccs.no/research/sp2-co2-transport/co2-pipeline-integrity/particular-challenges-to-co2-pipeline-transport/


For liquids, the speed of sound is roughly 1000 m/s, while the speed of ductile fractures typically is on order of 100-300 m/s. Thus, long running (ductile) fractures never take place in high pressure liquid pipelines. However, when dense-phase CO2 is depressurized, a gas-liquid (two-phase) mixture will form. The speed of sound in such a mixture can be lower than 100 m/s while the pressure is sufficiently high to drive the running fracture, so that the fracture will not arrest. This situation is illustrated in the animation below, where one can see the profile opening of the pipe in green color, and the pressure profile in the blue line during a simulation (pure CO2) using the coupled code developed in Task 2.1. One can clearly see in the animation that no crack arrest will take place.


For liquids, the speed of sound is roughly 1000 m/s, while the speed of ductile fractures typically is on order of 100-300 m/s. Thus, long running (ductile) fractures never take place in high pressure liquid pipelines.

However, when dense-phase CO2 ( and other gas pipeline) is depressurized, a gas-liquid (two-phase) mixture will form. The speed of sound in such a mixture can be lower than 100 m/s while the pressure is sufficiently high to drive the running fracture, so that the fracture will not arrest. (when the speed of sound of the medium is lower than the speed of ductile fracture)

This situation is illustrated in the animation below, where one can see the profile opening of the pipe in green color, and the pressure profile in the blue line during a simulation (pure CO2) using the coupled code developed in Task 2.1. One can clearly see in the animation that no crack arrest will take place.


In a situation where the saturation pressure is slightly lower either due to higher pipe pressure or lower temperature, the same pipeline material is able to arrest the running fracture. This is shown in the animation below.

Opening of the pipe in green color, and

Pressure profile in the blue line

- No Arrest


http://434113txicu25pflj3lqxy8nen.wpengine.netdna-cdn.com/wp-content/uploads/2013/10/noarrest.mp4?_=1

Opening

Pressure profile

- Arrest


Opening

Pressure profile


Animation: https://www.nde-ed.org/EducationResources/HighSchool/Sound/js_apps/speedInMaterials/

Summarizing:(Ductile fracture propagation occurs, when the speed of sound of the medium is lower than the speed of ductile fracture)




Summarising, the ductile fracture propagation in gas pipeline is characterised by the following aspects:

the driving force is coming from the energy release from gas expansion during escape;

generally the crack path is linear along the top pipe generatrix; the crack velocity is usually up to 300 m/s; there is a prominent effect of the pipeline steel and the backfill type (soil or

water) on the fracture propagation process; there is a strong effect of the gas nature and composition on the fracture

propagation process; there is high plastic deformation field associated with the near-the-crack; the prevention is essentially made by choosing an adequate level of pipe

toughness; a possible impediment of the crack propagation is by the use of echanical

crack arrestors.



The determination of the toughness values required for arresting ductile fracture propagation, generally measured by Charpy-V impact tests, has beenhistorically based on the use of empirical data from full scale burst tests.Several models in form of predictive equations, which states the minimumrequired value of the Charpy energy as a function of both pipe geometry andapplied hoop stress (Figure 1), have been set up using data from more thanone hundred of full scale burst tests, and proposed to that goal (Eiber andBubenik (1 ), Maxey (2), Demofonti et al (3)).

Figure 1 -Limit of reliability of existing empirical models



THE FULL SCALE TEST APPROACHBy the 70's, when the ductile fracture propagation arose as one of the key point for gas pipeline design in terms of both safety and economic loss, thefull scale burst testing has been recognised as the only reliable test of fracturebehaviour for gas pipeline. In particular, the full scale burst test can beconsidered as an indispensable tool for: assessing the minimum toughness level to arrest the ductile fracture

propagation in a definite short length for a specific pipeline in a specificproject;

providing the experimental data concerning the fracture behaviour, in relation to the design parameters (linepipe diameter and thickness, steel grade, hoop stress level, gas nature, etc.), for the predictive models development and validation.



In fact a full scale test provides a direct indication of the level of toughnessnecessary for crack arrest and, when suitably instrumented, provides also alarge amount of extremely useful data as crack propagation speed, pressuredecay, elasto-plastic strain field associated with the crack tip, etc. These datamay be compared with those predicted by the various models, providing bothconfirmation of reliability and the basis for further refinement (Demofonti et al(4), Pipes and Morrison (5)). A good example of the capability of the full scaletest approach to be an indispensable tool for ductile fracture propagationcontrol was the case of the of offshore-shore pipelines: the constraint effect due to the water backfill was correctly understood only when a reduced number of burst tests (Maxey (6), Demofonti et al (7)), some of which carried out by CSM at water depth down to 30 meters (7), were performed. Thanks to the instrumentation used at that time the over-pressure field due to the watercompression acting at the crack tip during the fracture propagation wasmeasured and the resulting decrease in the applied hoop stress (about 30%)was estimated.



Despite the high cost necessary to perform a full scale burst test, the technical and economical importance of the results coming from these tests,both for pipe makers and gas companies, pushed for carrying out a largenumber of full scale tests in the last 25 years (Figure 2). These tests werecarried out by several actors, as Battelle Memorial Institute, Centro SviluppoMateriali and British Gas, on behalf of several pipe makers, gas companiesand international organisations interested in funding the increase ofknowledge in this field; see for example the activities sponsored by theEuropean Pipeline Research Group (Demofonti et al (8)) As a consequenceof these testing activities, a certain number of full scale burst test databasehave been developed (CSM, AGA, EPRG, etc.) where the main testparameters (pipeline geometry, test temperature and pressure, pipestoughness, etc.) and results (propagation and arrest pipes. crack speed, etc.)are reported. In particular, the CSM database comprises the results of morethan 120 burst tests (as well as the full results of the 27 tests carried out byCSM in its test site in Sardinia) on pipes with diameter ranging from 406 to1422 mm, wall thickness from 4.8 to 30.5 mm, steel grade from X52 to X 100,and carried out in both on-shore and offshore conditions using air, natural gasor rich gas. It is noteworthy, the up-to-date cost of this huge amount oftestingis more than 60 million US dollars.





As it is evident in Figure 2, the main effort in terms of experimental activitieswas done in the 70's and in the first half of the 80's. At the end of the 80's, thecomprehension of the phenomenon and the relevant predictive models were good enough to justify the full scale burst testing decrease. The full scaleburst testing revival in the last five years is strictly related with thedevelopment of new high grade pipeline steels (API X70) for newapplications (higher pressure, richer gas). Under these conditions the straightextrapolation of the existing predictive models is not allowable, and thereforeit is necessary to investigate the full scale behaviour of these new pipelinesteels in terms of ductile fracture propagation (Mannucci et al (9)).



Figure 2- Full scale burst tests performed in the last 25 years (CSM database)

THE FULL SCALE BURST TESTThe actual capability of a pipeline to arrest a propagating ductile fracture under certain operating conditions can be determined by a full scale burst test,where a longitudinal crack is artificially initiated. Only few organisations allaround the world are able to perform a full scale burst test. Since many years,the CSM is one of the world leader in conducting such full scale tests onpipes in both on-shore and off-shore conditions (see Figure 3 and 4), using airor methane as pressurising medium (pipe diameter can reach 1422 mm,thickness up to 30 mm and internal pressure as high as 20 MP A). The testduration is usually less than 500 ms, and the acquisition system should beable to handle data on the crack propagation speed and the pressurebehaviour as well as data concerning the pipe deformation and the loadsacting on pipes. During a conventional burst test more than I 00 sensorsignals have to be gathered, managed and analysed.



Figure 3 - Off-shore burst test performed Figure 4 - On-shore burst test performed by CSM in open sea (30m depth, (7)) by CSM using natural gas




EXPERIMENTAL SET-UPThe pipeline under investigation (typically 70 m long and consisting of severalpipes welded together having an increasing toughness from the centre) is located generally in the middle of existing permanent line composed by tworeservoirs (Figure 5) long enough to guarantee, during the whole crackpropagation on the central test pipes, the same driving pressure, which wouldact on a pipeline of indefinite length. If the line to be tested is an on-shore line,the whole test section is fully covered by soil (1m or more) that is lightlycompacted to reproduce the actual operating conditions. In case of an offshore line, all the test section has to be immersed into several meters of water, according to the requirements. Under controlled temperature conditions (so to assure the fully ductile fracture propagation) the test pipeline fully instrumented is pressurised at the desired hoop stress, by means of air or natural gas according to the requirements.

Figure 5 - Conventional layout of full scale burst test.




The burst is usually caused either using an explosive charge, able to create athrough thickness cut long enough to guarantee the break conditions on pipe, or creating a part wall cut by machining the pipe thickness, and afterwards acts on that cut by means of mechanical devices in order to create a through thickness critical cut (the latter is used by CSM for the off-shore testing). After the crack initiation, the fracture propagates on the upper pipe generatrix at a very high speed in both test line sides, sustained by the driving force assured by the gas decompression at the crack tip. The first and most important result is available immediately by an inspection after the test: the pipe on the central test line, which eventually causes an arrest of the crack, determines the minimal toughness requirement for the examined conditions. Other results areprovided by the data acquisition system, after proper manipulation, andconcern the measurement of fracture kinematics, gas pressure inside pipes,etc. as better described in the following.

TEST INSTRUMENTATIONIn a full-scale burst test two different types of instrumentation can be used on

test pipes. These two types can be conventionally named "conventional" and "extra instrumentation. The conventional instrumentation is used to measure:

the crack propagation speed, by means of Timing Wires made by electricalcables, so an on-off signal indicates when the crack arrives on a definite spot on the pipe generatrix; usually the Timing Wires are spaced each 1 meter or less along the whole test line;

the gas decompression behaviour in side the test pipes, by means of pressure transducers; a number of transducers ranging from 8 up to 10 are usually used on purpose;

the test temperature, by means of thermocouples (usually in number of 3 or more).





The extra instrumentation (in the addition of the conventional one) is used forobtaining additional information on the pipe elastic and plastic deformation, on the gas decompression behaviour on pipe walls and on the behaviour ofthe backfill during the fracture process. This is especially used when dataconcerning the fracture process at the crack tip have to be gathered andafterwards compared with those predicted by analytical or FEM models (finite element method) . In particular this type of instrumentation can be used to obtain information on the following aspects of the fracture phenomenon:



elastic deformation on pipe associated with the fracture process, by means of electrical strain gauges, fixed to the internal and external pipe walls, to measure the strain associated with the propagation of the fracture;

plastic deformation on pipe associated with the fracture process, by means of grid lines traced on pipe for plastic strain measurement after the test;

gas decompression behaviour in the flaps zone behind the crack tip during the crack propagation, by means of internal pressure transducers located on pipes and placed along the pipe circumference starting from top pipegeneratrix, to measure the pressure decay at the crack tip in circumferential direction before and after the crack arrival;

behaviour of the backfill of soil during the fracture process, by means of soil pressure transducers located both on the external pipe walls and embedded in the trench soil to measure any backfill loading.



Figure 6 shows a CSM test line fully instrumented by Timing Wires, pressuretransducers, strain gauges, load cells and soil pressure transducers. It is good manners to monitor and record each sensor signal by two independentsystems, in order to increase the reliability of the measurement. A typical testlayout of a full scale burst test carried out by CSM is reported in Figure 8together with the test results in terms of crack path and propagation speedcompared with the actual CharpyY toughness of the test pipes. Figure 7shows a typical view of an on-shore line after the test.

Figure 6 - Test line fully instrumented (CSM test)


Figure 7 - View of an on-shore test line after the burst (CSM test)


Figure 8 - Typical full scale burst test layout and results (test carried out by CSM on behalf of EPRG, (8))




FUTURE TRENDThe steady increase in natural gas need on the European market compels to develop new technological solutions for the long distance transportation ofhuge amount of gas from remote areas. For making this way economicallyviable one of the key point is to increase the operating pressure (andconsequently the applied hoop stress); in the last decade new high gradepipeline steels (API steel grade higher than X70 and up to X100 or more) arebeing developed on purpose (9). The ductile fracture behaviour of these newmaterials lies outside the field covered by the existing experimental data(Figure 1) therefore an extrapolation is possible but not reliable. To extend theapplication field of the empirical models a wide range full scale test campaignshould be undertaken. The design and building of pipelines for carrying richgas mixtures represents an option more and more interesting from the gascompanies point of view; gas rich o f heavy components means in fact greateramount of energy conveyed under the same conditions. Nevertheless thefracture control when rich gases are involved required significantly high levelsof fracture propagation resistance. Given that it is difficult to develop simpleguidelines to adjust the existing predictive models, the full scale burst testremains one of the main way to face the question.


Moreover with the aim to study the fracture behaviour of new high gradepipelines steels, in the last ten years FEM finite element models simulating the fracture phenomenon have been developed (4). In this context the full-scale burst test, equipped with "extra instrumentation" mentioned above, is afundamental tool for obtaining primary information in terms of physicalparameters of rracture phenomenon to develop and validate the models.Finally, the reliability of any theoretical prediction will be only as good as therange of the experimental data from which it has been derived. Predictionsoutside that range require confirmation by additional full scale burst tests.Therefore, while pipeline design continues to evolve towards higher strengthsteels, higher operating pressure and richer gases, the process of full scaleburst testing and associated refinement of predictive models will be acontinuing process (5)

SampleQMS-ITP01



QMS-Sample ITP1


RRHApproved ProcedureTBASubmit

Procedure For Approval

Visual / Dimensional Procedure

4

RHHApproved MPSTBASubmit

Procedure For Approval

Manufacturing Procedure Specification3

HHHMinutes of MeetingTBAMeeting

Pre-inspection / Kick Off Meeting

2

HHH

Approved Inspection and Test

Plan

ITP k065_2016

Submit ITP for Approval

Inspection And Test Plan1

3rdCM

INSPECTIONVERIFICAT

IONINSTRUCTIONS

PROCEDURE/CRITERIA

CONTROL POINT

PROCESS DESCRIPTIONRef

H: Hold Point, W: Witness Point, R: Review, M: Monitor


RRHApproved ProcedureTBASubmit Procedure

For Approval

Field Weldability Procedure

7


For Approval

Mechanical Testing Procedures

6


For ApprovalNDT Procedures5

3rdCM

INSPECTIONVERIFICAT

IONINSTRUCTIONS

PROCEDURE/CRITERIACONTROL POINT

PROCESS DESCRIPT

IONRef



MMM

--Process computer and technical standard

MPS Korea_2016 Q-4

Rolling temperature Rolling reductionWidth & thickness

Strip Hot Rolling

d

MMM


MPS Korea_2016 Q-3

Heating temperature

Slab Heating

c

MMM


MPS Korea_2016 Q-2

Slab conditionSlab Continuous Casting

b

M R

M R

M R

Ladle analysis data in L4

Process computer and technical standard

MPS Korea_2016 Q-1

Chemical composition

Steel Making Ladle Analysis

a



M R

M RH

Information sheet of coiled strip in MES and L4

Process computer and working instruction

MPS Korea_2016 M-1

TraceabilityChemical compositionMechanical properties of hot coil Mechanical properties of hot coil

Strip Visual and Dimension Inspection

f

M R

M R

M R

Process computer and technical standard

MPS Korea_2016 Q-5

Strip Mechanical properties

Strip Mechanical Testing

e



W R

W R

M R

--Process computer and working instruction

MPS Korea_2016 M-5

No requirement.Strip UTj

MMM

Operating sheets and logging


MPS Korea_2016 M-4

WidthShape of strip edge

Strip Edge Milling

i

MMM



MPS Korea_2016 M-3

TraceabilityShear/End Welding

h

MMM

List of coil charging

Working instruction

MPS Korea_2016 M-2

TraceabilityWidth & thickness

Coil Openg



MMM

Operating sheets


MPS Korea_2016 M-8

Outer flash conditionInner flash height

Flash Trimming

m

M R

M RM

PQRProcess computer and working instruction

MPS Korea_2016 M-7

Heat inputVelocitySqueeze

HFWl

MMM

--Process computer and working instruction

MPS Korea_2016 M-6

Strip surfaceCircumferential length

Cold Forming

k



MMM



MPS Korea_2016 M-12

Length Cutting to Length

q

MMM

Operating sheets


MPS Korea_2016 M-11

ReductionOutside diameter

Sizing and Straightening

p

M R

M R

M R

Temperature chart


MPS Korea_2016 M-10

Heat treatment typeHeat treatment temperatureHeating width

Heat Treatment

o

W RWM

Inspection chart


MPS Korea_2016 M-9

Longitudinal imperfections in weldMinimum wall thickness along the weld seam

Online Seam UT

n



MMM

Operating sheets


MPS Korea_2016 M-15

Shape of pipe endEnd Beveling

t

W RWH

Material test data in L4

Proce

Api5l part 1 of 2b

Documents

Transcript of Api5l part 1 of 2b