16-2 Recipientes a Presion

GERENCIA COMPLEJO BARRANCABERMEJA Volumen 3, Job Instruction 16 - 2

TECHNICAL SPECIFICATIONS FOR PRESSURE VESSELS

Rev. 0 Pág. 1 de 13ESPECIALIDAD: EQUIPO ESTATICO


Rev. No Fecha Descripción Elaboró Revisó Aprobó0 27–08 -2004 Emisión para implementación de Propuestas de Mejoramiento en GCB JSR JCPM LSPB




INDICE

1. GENERAL1.1 SCOPE1.2 REFERENCES

2. DESIGN2.1 GENERAL REQUIEMENTS2.2 LOADING2.3 SHELLS AND HEADS2.4 VESSEL SUPPORTS2.5 DISCONTINUITIES2.6 NON-PRESSURE RETAINING COMPONENTS WELDED TO SHELL2.7 NOZZLES AND MANWAYS2.8 SPECIAL CONSIDERATIONS FOR ELEVATED TEMPERATURE DESIGN

3. MATERIALS3.1 GENERAL3.2 SHELL HEADS AND OTHER PRESSURE CONTAINING COMPONENTS3.3 NOZZLES AND MANWAYS3.4 SMALL CONNECTIONS3.5 VESSEL SUPPORTS AND OTHER SUPPORT MATERIAL3.6 INTERNALS, INTERNAL BOLTING AND INTERNAL SUPPORTS3.7 ALLOY LINING

4. FABRICATION4.1 WELDING4.2 HEAT TREATMENT4.3 ALLOY LINING4.4 TOLERANCES4.5 NOZZLES, MANWAYS AND HANDHOLES

5 TESTING




1. GENERAL

1.1. Scope

a. This specification covers the requirements for design, materials selection, fabrication, inspection, and testing of carbon steel fusion welded vessels, and is intended to supplement the applicable Pressure Vessel Codes.

b. Exceptions or variations shown in the Project Specifications take precedence over requirements shown herein.

1.2 References (Latest Edition and Addend)

ASME Boiler and Pressure Vessel Code, Section VIII, Division 1, Pressure Vessels. ASME Boiler and Pressure Vessel Code, Section VIII, Division 2, Pressure Vessels. ASME Boiler and Pressure Vessel Code, Section I, Power Boilers. ASME Boiler and Pressure Vessel Code, Section II, Material Specifications. ASME Boiler and Pressure Vessel Code, Section IX, Welding Qualifications. ASME publication , Stresses in Large Horizontal Pressure Vessels and piping ASTM Material Specifications(A193 / A193M ; A194 / A194M ; A320 / A320M ; A370 ; A453 / 453M) AWS/ASME Specifications for welding electrodes ( A5.1 ; A5.17 ; A5.18 ) ASME B16.5, Pipe Flanges and Flanged Fittings. ASME B20.1 Pipe threads, General Purpose ASME B16.20 Metallic Gaskets for pipe flanges. ASME B16.47 Large diameter steel flanges ASME B46.1, Surface Texture National. State and Local Laws and Codes CCCSR, Código Colombiano de Construcciones Sismo Resistentes. NACE TM-01-70 / 75 Surface preparations Standards.

2. DESIGN

2.1 General Requirements

a. The design, materials, fabrication, inspection and testing of pressure vessels shall conform to the latest edition and addenda of the Code specified on the Project Specifications and as specified by the governing legal authority. In cases of conflict between requirements, the most restrictive requirement shall govern.

b. The vessel designer shall be responsible for the accuracy of all computer programs used for the stress and thermal analysis of the vessel and components.

c. The general Contractor shall be responsible for the compatibility of all flanges matting with piping. The type, design and details for nozzle flanges which are not in accordance with a standard listed in the ASME Code shall also be the responsibility of the Contractor and must be in accordance with the applicable codes and good engineering practice.

d. The Contractor shall be responsible for determining the need and the acceptable methods to perform any special analyses above the minimum calculations required by the ASME Code.




e. Where "M.R." is specified, it indicates that it is the Manufacturer’s and/or Contractor’s responsibility meet the requirement in accordance with all applicable codes and standards, including any additional requirements specified in project specifications.

f. Design thickness specified are minimum unless otherwise noted.

g. The contractor and/or the manufacturer of the equipment must be an approved and accepted as a reliable fabricator stenciled with the ASME label.

h. The equipment must be registered by the contractor and/or manufacturer before the National Board Association.

2.2 Loading

a. External loads due to wind and earthquake shall be determined in accordance with the procedures of the governing Code and/or the data specified in the Project Specifications.

b. Vertical vessels and horizontal vessels, including their supports, shall be capable of supporting a full load of water. at atmospheric pressure, in the erected position.

c. Vertical vessels shall be checked for vibration due to wind or other sources to ensure their structural safety. Both stress and deflection limits will be met.

d. Where "delta P trays (total) or Delta P upflow (total)" is specified, thin pressure drop shall be added together with any liquid static head in determining the bottom design pressure of the Vessel.

2.3 Shells and Heads

a. The design thickness, in accordance with the Specified Code, shall not include any material used for applied corrosion resistant lining or the cladding material on integrally clad plate.

b. Thickness for the different vessel elements (shell, heads and transitions) must be designed in accordance with the operation conditions such as : internal / external pressure, geometry of the vessel(cylindrical or spherical),code permissible stress for the selected material related to design temperature, corrosion allowance, fabrication allowance, standard thickness ,etc.

c. The effects of external primary mechanical loads plus design pressure and the effects of secondary stresses due to differential thermal expansion shall be investigated, and the resulting combined stresses and deflections shall be evaluated. It is the responsibility of the Contractor to specify the governing load cases and critical locations.

2.4 Vessel Supports

a. Vessel supports (e.g., skirts, lugs, legs and saddles) shall be designed to withstand the worst probable combination of live and dead loads anticipated during the normal life of the vessel, exclusive of allowance for corrosion.

b. A minimum of 1/16 inch (1.6 millimeters) additional thickness shall be provided for corrosion allowance.




c. Stresses due to differential thermal expansion and frictional forces from sliding supports shall be considered in the design.

d. All horizontal vessels shall be supported by saddle supports fabricated to fit the outside surface of the vessel within the tolerances required by the design to prevent excessive localized stresses in the shell. Saddles shall not be placed over vessel girth welds and are to be continuously seal welded to the shell.

2.5 Discontinuities

Sharp discontinuities located in regions subjected to operational cyclic mechanical and/or thermal stresses shall be avoided to prevent cracking due to thermal fatigue.

2.6 Non-Pressure Retaining Components Welded to the Shell

Load bearing welds attaching non-pressure retaining parts to pressure retaining parts shall be designed according to the same allowable stress basis for primary membrane tensile (compressive) and shear stresses as required for pressure retaining components.

2.7 Nozzles and Manways

a. When the inside diameters of nozzles are specified they shall be maintained. When the inside diameters of manways are specified, they shall be considered as minimum.

b. Class 150 flanges are not permitted for design temperatures over 700°F (370°C) or for pressure relief valve connections: Class 300 flanges shall be used as a minimum instead.

c. Integrally reinforced nozzles or balanced integral reinforcement in both the nozzle neck and vessel are preferred, although and built-up construction is permissible. Caution shall be exercised for connections which must receive equipment to insure that the inside diameter is large enough and the flanges match.

d. External reinforcing pads shall have a minimum of one vent hole except that pads for nozzles greater than 16 inch NPS shall have a minimum of 2 vents, and nozzles in excess of 36 inch NPS shall have 4 vents. Pads installed by sections shall have at least one vent per section. All vents shall be tapped for future plugging with a maximum 1/4 inch NPS hole.

e. Slip-on flanges are not permitted if the flange design temperature exceeds 500ºF (260°C) or when the flange rating exceeds class 300. Slip-on flanges, when permitted, shall be double welded and vented with the use of 1/8 inch diameter pre-drilled holes through the hub.

f. Where 125 Ra is specified for flange surface finish, the range for acceptance shall be 125 Ra minimum to 250 Ra maximum. Finishes shall be judged by visual comparison with surface finish roughness standards conforming to ASME B46.1. It is the Contractor's responsibility both to comply with the above finish requirements and to assure that such flange finishes be protected from damage during shipping, storage and installation Where flange surface finish is not specified, it is the responsibility of the contractor for the gasket specified.

g. The general Contractor shall give special consideration for the prevention of overstressing the flange or bolts during gasket seating, when Class 300 and lower flanges are used with spiral wound or metal gaskets.




h. Flange classes listed in the project specifications are based on design pressure temperature conditions only and do not account for external loads due to piping reactions. The design of all flanges shall account for external loads imposed by piping reactions. Consideration shall be given to differential thermal expansion for dissimilar joints and transient thermal conditions such as start-up shutdown and equipment failure.

i. Nozzles and manways shall not be located in tray downcomers.

2.8 Special Considerations for Elevated Temperature Design

For design temperature of 800°F (427°C) and higher the design details for nozzles, supports, and other attachments to the vessel shell shall be free of high local stress concentrations. Design details using fillet welds shall be avoided unless grounded to a smooth radius.

3. MATERIALS

3.1 General

a. Materials shall be specified by ASTM numbers or ASME numbers in this specification. ASTM specification numbers are prefixed by A and corresponding ASME Specification numbers are prefixed by SA. Pressure Vessel materials shall be in accordance with ASME Specifications. Non-pressure parts may be in accordance with ASTM specification.

b. Materials conforming to other standard specifications, equivalent to those specified, are acceptable. Equivalent material specifications are those that conform to chemistry, mechanical properties, quality, testing, and inspection. The general contractor is responsible for equivalency of materials when substitutions are made.

c. All material used in the vessel(s) shall be brand new and the same type and grade specified for the Project Specifications.

d. Each plate or forging shall be legibly stamped or stenciled showing grade number and plate or forging -number. When metal stamping is done it shall preferably be on the long edge of each component as it leaves the mill. Metal stamping on rolled surfaces shall be done with a "low stress" stamp.

3.2 Shell Heads and Other Pressure Containing Components.

a. Steel plate for shells. heads, and other pressure parts shall be as specified.

b. Where carbon steel is specified, SA 285 Grade C is the minimum quality acceptable.c. Where killed carbon steel is specified. SA 515 or SA 516 is required. SA 516 is required when the vessel

thickness exceeds 2 inches.

3.3 Nozzles and Manways

a. Flange rating shall be in accordance with material group 1.1 of ANSI B16.6 unless otherwise specified.

b. Nozzle flanges for thermowell connections may require a higher flange rating than the main attachment nozzles, depending on thermowell flange material. Therefore, contractor shall check all thermowell flange material rating and increase equipment mating flange rating where required.




c. Minimum material requirements:

ITEM For Carbon Steel Vessels For Killed

Necks (fabricated from pipe)Pipe 24 inch NPS and lessPipe 16 inch NPS or overFlangesIntegrally reinforced nozzles, weldingneck, welding neck flanges, slip-on, or lap joint flanges

Plate where permissible by code)

SA 106 Gr A

SA 105

SA 515 or SA 516

SA 106 Gr B

SA 105

SA 515 or SA 516

d. Corrosion allowance for nozzles and manways shall be at least equal to that specified for the vessel shell.

e. Bolt holes in flanges of nozzles and manways located in heads of vessels shall straddle the principal centerlines of the vessel or lines parallel thereto. Bolt holes in flanges of nozzles and manways located in shells shall straddle the vertical centerline of the vessel.

3.4 Small Connections

a. Threaded fittings or tapped holes are not permitted.

b. The minimum size of nozzles shall be 1 inch NPS (Nominal Pipe Size) except that for alloy lined nozzles the minimum size is 1-1/2 inch NPS.

3.5 Vessel Supports and Other Support Material

a. Material for rings, lugs and legs supporting vessels and the upper three feet of support skirts welded directly to the vessel, or to reinforcing rings welded to the vessel, shall be the same material as the shell when the design temperature is greater than 650°F. Otherwise, the material for the skirt, rings, lugs and legs shall be A285, A36 or better.

b. Material for vacuum stiffening rings shall be the same material as the shell when the design temperature is greater than 650°F (343°C). When the design temperature is 660°F (343:C) or less the material shall be A285, A283, A36, or better.

c. Steel plate for base rings, reinforcement for skirt openings. saddles, external lugs for platforms, ladders, insulation supports, pipe supports and other attachments shall be A285, A283, A36 or better. Angles and rods shall be A36.

d. The contractor shall determine the need and placement of vessel shell attachments for handling internals. attaching hardware etc.

3.6 Internals, Internal Bolting and Internal Supports

a. Pipe for internals shall be A 106 Gr B. Plate, bars, and shapes shall be A 285, A 283, A 36, or better.

b. Internals shall be alloy or alloy lined in alloy lines portions of a vessel.




c. Bolting for distributors, baffles, or other miscellaneous items, not furnished by the tray supplier, shall be the same or similar alloy as the internals, or as specified.

d. Drawings and instructions for fabrication and installation of tray and mesh blanket supports attached to the vessel shall be furnished by the appropriate supplier of the vessel internals. The vessel attachments shall be installed in accordance with those instructions, ant these specifications, by the vessel manufacturer. It is the responsibility of the vessel manufacturer to supply, or cause to be supplied, all material required for the fabrication of the vessel attachments for the support of internals.

e. Internal support rings shall be the same material as the shell in killed steel vessels.. They shall be continuously welded on the top ant stitch or continuously welded on the bottom when carbon steel and continuously welded both sites w hen alloy.

f. Lugs welded to the shell for the support of internals shall be the same material as the shell in killed steel vessels. In the lined portion of vessels, lugs shall be alloy corresponding to the lining.

g. Unless otherwise specified, lugs and rings for internal supports in lined portions of vessels may be welded directly to the lining only if the vessel is lined with integrally bonded lining or weld deposit overly meeting the requirements of Paragraph UCL-11(a) and (c) Section VIII Division 1 of the ASME Code.

3.7 Alloy Lining

a. Alloy lining material and thickness shall be as specifies on the Project Specifications.

b. Alloy lining material for nozzles and manways shall be the same as for the vessel.

4. FABRICATION

4.1 Welding

a. All welding shall be done by a metal arc process. All shell and head joints shall be double welded butt joints with full penetration. Double welded groove joints shall have their root passes back gouged to sound metal on the reverse side before welding on that side. In cases where double welding is impractical, the root pass shall be made by the Gas Tungsten Arc Welding (GTAW) process.

b. The use of the Flux Cored Arc Welding (FCAW) and Gas Metal Arc Welding (GMAW) processes shall be approved by the ECOPETROL.

c. The Flux Cored Arc Welding Process shall utilize an external shielding gas and is not permitted for single sided tee or corner joints.

d. The Gas Metal Arc Welding process in the short circuiting mode (GMAW - S) may be used for the following applications only:

The root pass for any material thickness.

Complete groove or fillet welds providing that the wall thickness does not exceed 1/4 inch (6 mm)

Tack welds, temporary attachments and other applications where the weld made by this process is completely removed.




e. The Gas Metal Arc Welding process in the spray transfer mode shall not be used for the root pass.

f. Covered welding electrodes for non-alloy welding shall be in accordance with Specification AWS A 5.1, ASME SFA-5.1

g. Bare electrodes shall be in accordance with the following :

Welding Process Electrode

Submerged Arc Welding AWS A 5.17. ASME SFA-5.17Inert Gas Welding AWS A 5.18, ASME SFA-5.18Flux-Cored Arc Welding AWS A 5.20. ASME SFA-5.20

h. Deposited weld metal mechanical properties shall conform to the ASTM Requirements for the base metal. Low-alloy, high strength weld material shall not be used unless the vessel is required to be postweld heat treated (PWHT) at a temperature of 1150°F (620°C) minimum.

i. Welding in conjunction with alloy lining shall be done with covered electrodes made in accordance with the specifications listed, or alternated as covered by note below.

ASTM Specification Electrodes

Cladding Applied lining Alloy To Steel Alloy to Alloy

A 263 A 240 Types 405 or 410S (1) (1)A 264 A 240 Type 304 (1) (3)A 264 A 240 Type 304L (1) (4)A 264 A 240 Type 316 (2) (5)A 264 A 240 Type 316L (2) (6)A 264 A 240 types 321 or 347 (1) (7)A-265 B 127 (8) (8)

Specification Electrode Classification(1) AWS A5.4, ASME SFA-5.4 E309L(2) AWS A5.4, ASME SFA-5.4 E309Mo(3) AWS A5.4, ASME SFA-5.4 E308(4) AWS A5.4, ASME SFA-5.4 E308L(5) AWS A5.4, ASME SFA-5.4 E316(6) AWS A5.4, ASME SFA-5.4 E316L(7) AWS A5.4, ASME SFA-5.4 E347(8) AWS A5.11. ASME SFA-5.11 ENiCu-7




NOTE: When inert gas shielded or submerged metal-arc processes are used, stainless-filler metals made in accordance with Specification AWS A5.9, ASME SFA-5.9, with composition similar to those listed above, or Monel (nickel copper alloy) in accordance with AWS A5.14, ASME SFA-5.14 shall be used.

j. Paragraphs NF-7 and NF-14 of Appendix NF in Part UNF of Section VIII of the ASME Code are mandatory for nonferrous types of cladding or applied lining.

k. All pressure shell weld joints of categories A or B shall be Type No. 1 full penetration butt welds in accordance with UW-3 and table UW-12 of the ASME Code.

l. Nozzles and manways and their reinforcement shall be attached to the vessel with full penetration welds.

m. Backing up steps, if used, shall be removed.

n. Circumferential welds shall be located to facilitate visual inspection with all internal equipment in place.

o. Seams in supporting skirts shall be made with full penetration butt welds. Connections between skirts and vessel heads shall be made with a smooth flat faced weld, unless otherwise shown The width of the weld shall be at least equal to the skirt thickness, and its height approximately twice its width.

p. All welding directly to the base metal shall be completed prior to final heat treatment.

q. Each category A or B pressure retaining weld in accordance with figure UW-3 of the ASME Code shall be spot radiographed, as a minimum requirements, Each spot radiograph shall be a minimum of six inches in length and in accordance with the ASME Code. All welds to be cowered by nozzle reinforcing pads and at least one weld intersection shall be included. Nozzle welds shall be spot examined by magnetic particle or dye penetrative as a minimum requirement .

r. Welds in vessel shells 2 inches and greater in thickness shall be 100% examined by ultrasonic in accordance with the ASME Code, after final post weld heat treatment.

4.2 Heat Treatment

a. Postweld heat treatment (PWHT) shall comply with the governing Code requirements, or as specified.

b. Flange facings must be protected against oxidation during heat treatment.

c. When postweld heat treatment is required, one Brinell hardness reading shall be taken on the inside (except in alloy lined portions of vessels) of each shell section, head, longitudinal weld, and nozzle, and each longitudinal, girth and nozzle weld after final postweld heat treatment; and no reading shall exceed a value of 200.

4.3 Alloy Lining

a. In this specification the term "Alloy Lining” is a general term that does not imply a specific fabrication or manufacturing process.

b. Strip lining is not allowed unless specified on the project specification.

c. Alloy lining for shells and heads shall be integrally bonded cladding or weld deposit overlay.




d. When integrally bonded clad plate is the alloy lining used, the lining shall be cut back at all seams to permit backwelding of the base metal. Weld metal shall be ground flush and fully covered with the applicable weld deposit overlay in paragraph IV-A-9 of this specification. The weld deposit overlay shall be at least as thick as the lining but no greater than twice its thickness.

e. When integrally bonded clad vessels are used, a minimum of 10% of the clad surface, including no less than 1 square foot in each 10 square feet or fraction thereof, shall be ultrasonic examined for lack of bond after forming. The cladding shad be 100% ultrasonically examined in areas where attachments are to be welded directly to the cladding. Unbounded areas that cannot be encompassed by a 3 inch diameter circle shall be repaired by weld deposit overlay in accordance with paragraph IV-A-9 of this specification. When repairs in excess of 5 percent of the total examined area are required, the vessel shall be 100 percent ultrasonic examined. Repaired areas and weld deposit overlay at weld seams shall be 100% liquid dye penetrative examined in accordance with ASTM E165. Ultrasonic examination shall be in accordance with ASTM A578 SD6 for spot examination or S7 for 100%, examination.

f. The weld overlay shall be applied circumferentially to the vessel and shall be relatively smooth with no notches and undercuts that would act as stress intensifiers. Flaws on the surface of the base metal that would interfere with bonding of the overlay shall be removed by grinding.

g. All weld deposit overlay, whether by manual or automatic procedures, shall be 100% liquid dye penetrative (PT) examined in accordance with the methods described in ASTM E 165. When the overlay involves two passes (layers) and the procedure uses an intermediate heat treatment with cooling to room temperature prior to applying the second layer, each layer shall 1OO% PT examined. Weld deposit overlay machined surfaces shall be 100% PT examined after final heat treatment. Weld deposit overlay shall be spot PT examined (a minimum of 10% of the surface, including no less than 1 square foot in each 10 square feet of fraction thereof) after final heat treatment and shop hydrostatic testing. Flange facings need not be included in the spot examination after hydrotest.

h. All cracks and fissures and circular defects greater than 1/16 inch ( 1.6 millimeters) diameter in weld deposit overlay shall be removed. Repaired areas shall be 100% re-inspected by liquid aye penetrative.

i. The weld deposit overlay procedure shad be qualified on base metal of the same composition as the vessel and thickness of one-half of the vessel thickness, or 2 inches (50 millimeters), whichever is less.

j. A minimum of two samples of the weld deposit overlay shall be taken from each overlayed shell section and head to confirm required analysis. Each manual weld overlay, such as those on girth seams and nozzles, shall also be sampled. Analysis to a depth of 3/4 of the required overlay thickness shall conform to the chemistry requirements for the alloy specified on the Project Specifications. Where automatic weld deposit overlay is applied by more than one welding operator, samples shall include deposits made by each operator.

k. Nozzles and manways in alloy lined pore of vessels shall be alloy lined and faced. The facing shall be made with weld deposit which is at least as thick as the lining when properly machined and of the same alloy as the lining When nozzles are lined with ferritic type 405 or 410S stainless steel linings, the facing weld deposit shall be made with type 309 welding electrode. The facing weld deposit for austenitic stainless steel linings shall be made with type 309 welding electrode for the first pass, and the welding electrode for the second pass shall be of the same or similar analysis as the lining.

l. The method of lining large nozzles and manways shall be by integrally bonded cladding or weld deposit overlay.




m. Tubular liners are not acceptable in nozzles greater than they shall 4 inch NPS. For nozzles 4 inch NPS and smaller tubular liners may be used. Those shall be welded to the alloy facing at the flange end. Attachment of the liner at the inside surface of the vessel may be by welding, flush with the vessel inside surface, or an expansion (contraction) collar. The final design details, accounting for the sustained and cyclic stresses due to the intended operation of the vessel, are the responsibility of the Contractor.

n. For hydrogen service. nozzles with tubular liners welded on both ends shall be vented with an l/8 inch NPS hole, drilled from the outside bathe OD of the liner and tapped for future plugging.

o. Solid alloy nozzles, are not recommended, and shell not be used at design temperatures above 450°F (232°C).

p. Austenitic stainless steel nozzles are not permitted.

4.4 Tolerances.

a. Vertical vessels shall be checked for plumpness. After the ring sections have been assembled, the outside surface of the cylinder shall not vary from a straight vertical line more than ¼ inch (6 millimeters) in any 20 feet (6000 millimeters), nor more than ¾ inch (19 millimeters) in the total length. When shell thickness is 4 inches (200 millimeters) or more the variation from a straight line shall not exceed 1- ¼ inches (31 millimeters) in the total length.

b. The maximum permissible offset for longitudinal joints shall be 1/4 inch (6 millimeters) and for circumferential joints, ½ inch (13 millimeters).

c. The maximum out-of-round variance of the specified code shall apply for all vessels, with the additional limitation that for vessels with internal trays any diameter may not vary plus or minus 1/2% from the nominal diameter, with a maximum variation in diameter from nominal of ½ inch (13 millimeters).

d. The overall length of the vessel, not including the skirt, shall be held within a tolerance of plus or minus ½ inch (13 millimeters) or 1/64 inch (0.4 millimeters) per foot of length, up to a maximum of plus or minus ¾ inch, whichever is greater.

e. The length of skirt shall be held within a tolerance of plus or minus 1/4 inch (6 millimeters).

f. The tolerances for nozzle locations shall be plus or minus 3/8 inch (10 millimeters) for elevation, plus or minus 1/4 inch for orientation, and plus or minus 1/8 inch (3 millimeters) for projection.

g. The maximum horizontal or vertical deflection of the machined faces of the gasket faces of nozzles shall be ½ ° or 1/32 inch (0.8 millimeters), whichever is greater.

h. The tolerance for manways shall be plus or minus ½ inch (13 millimeters) for elevation, orientation, and, projection, and 1/4 inch (6 millimeters) for tilt.

i. The maximum tolerance from a true base for internal tray supports shall be plus or minus 3/8 inch (10 millimeters).

j. The maximum variation in spacing between adjacent internal tray supports shall not exceed 1/16 inch (1.6 millimeters) per foot (300 millimeters), with a maximum of 1/8 inch (3 millimeters).




k. The tolerance for the maximum variance (distance between high and low points) individual tray supports with respect to the level plane shall be 0.30% of the nominal inside diameter, with a maximum of, 1/4 inch (6 millimeters).

l. The tolerance for the maximum variance of tray supports with respect to the vessel shall not exceed 1° from normal.

4.5 Nozzles, Manways and Handholes

It is the responsibility of the Contractor to assure that the placement and perfection of nozzles, manways and handholes will not interface with the proceed or internals. The inside edge shall be rounded.

5. Testing

1. The minimum metal temperature during pressure testing shall be in accordance with either (a), (b) or (c) below.

a. 60°Fb. 30°F above the minimum design metal temperature (MDMT)c. 30°F above the ductile to brittle transition temperature for all of the materials of construction. The

transition temperature shall be established from impact test data

2. Clean fresh water shall be the primary hydrostatic test medium unless use of a different medium is approved by ECOPETROL S.A. Hydrostatic testing of austenitic stainless steel lined vessels shall be done with potable quality water having a chloride content less than 50 ppm (parts per million). If chloride content is greater than 50 ppm, up to a maximum of 250 ppm, a sufficient quantity of sodium nitrate shall be added to provide a test medium of 0.5% by weight sodium nitrate solution. Water with a chloride content of greater than 250 ppm shall not be used for hydrotesting. Vessel(s) shall be dried thoroughly, immediately after draining, to prevent the possibility of evaporation and concentration of chlorides.

3. Welded attachments provided with vent holes shall be tested by pneumatic or hydrostatic pressure prior to postweld heat treatment and final hydrostatic test.

4. Alloy strip or sleeve linings for vessels and nozzles shall be given a pneumatic test to prove the soundness of the welds. In lieu of this, the welds may be inspected by liquid dye penetrate. Cracks and porosity shall be repaired and reinspected.

5. Test holes in strips and sleeves shall not be seal welded until all trapped moisture is removed.

6. Vessels which are to be shop hydrostatically tested in the horizontal position shall be supported adequately to prevent local stresses in the shell from exceeding 90% the yield strength of the material.

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