piping ppt

© Matthews Engineering Training Ltd

API 570

PIPING INSPECTION


API 570 Piping Inspection Code

570


API 570 COVERS IN-SERVICE INSPECTION OF PIPING

To fit in with the philosophy of ANSI B31.3‘DESIGN CODE FOR PROCESS PIPING’


THE SCOPE OF API 570

Mandatory:Almost any metallic piping system:•Raw and finished oil products•Raw and finished chemical products•Hydrogen/fuel/flare gas systems•Sour/waste systems etc

Optional:•Water,steam and condensate•Piping related to mechanical equipment•(pumps/compressors etc)•Pressure vessels•Domestic sewers etc•Everything< ½ in dia•Non-metallic piping


API 570 INSPECTION PRACTICES

Checks are needed for specific types of corrosion and cracking:

1. Injection points2. Dead legs3. CUI4. Soil /Air(S/A) interfaces5. Erosion and erosion/corrosion6. SCC7. Corrosion under linings8. Fatigue cracking9. Creep cracking10. Brittle fracture11. Freeze damage

We’ll look at some of these in more detail


INJECTION POINTS

Why is particular inspection attention (and TMLs)needed at

injection points ?

….and what are TMLs anyway


12in or 3D upstream

2nd change of flow

direction downstream

(or 7.6m after the first change)

INJECTION POINT INSPECTION AREAS

This area is known as:The

IPC(‘injection point circuit’)


API 570 INSPECTION METHODS

Internal

visuals

TMLs(4 quadrants)

Externalvisual


DEADLEGS

Deadleg

Corrosion rates are higher

around deadlegs

Redundant deadlegs should be removed


CORROSION UNDER INSULATION (CUI)



Almost total wastage of bolts



API identifies the areas that are most susceptible to CUI

Mist from cooling towers

Near steam ventsand deluge systems

Acid vapours


•All LCS pipework operating continually at –4<t<120 degC

•LCS pipework operating> 120 degC BUT INTERMITTENTLY

•Austenitic Stainless steel at 65-205 DegC (for SCC)

•Piping systems that vibrate a lot (insulation becomes damaged)

•Piping systems with damaged wrappings



CORROSION UNDER FIXED LININGS

In general ,API does not require removal of

linings for inspections…AS LONG AS THE LINING IS IN GOOD CONDITION

BUT


SOIL/AIR INTERFACES

All interfaces without cathodic protection


The API 570 rule is that you should inspect areas for CUI where the

insulation is damaged



RECOMMENDED EXTENT OF CUI EXAMINATION(BY CLASS)

Type of circuit

% NDT on areas with damaged insulation

% NDT on suspect areas

within CUI temperature

range

Class 1 75% 50%

Class 2 50% 33%

Class 3 25% 10%


EROSION AND EROSION-CORROSION LOCATIONS


•Control valves (especially when there is ‘flash-off’•Orifice plate•Pump discharges•Elbows•Pipe features that produce turbulence

TMLS FOR EROSION/CORROSIONDownstream of ………..


An example

EROSION/CORROSION


Erosion/Corrosion after flow-restriction

features


STRESS CORROSION

CRACKING (SCC)

Rule:In most circumstances,SCC is

due to


SCC ON A GAS PIPELINE COMPONENT


What is this?


API 570 GUIDE ON REPAIR PATCHES

D

Max D/2

Repair patch

Not permitted

25mm min radii


API 570 GUIDE ON REPAIR PATCHES

Requires a full repair sleeve

Min 2D


API 570 INSPECTION INTERVALS

The maximum permitted interval depends on pipe ‘class’

Class 1:Highest risk/consequence

Class 2 : ‘Medium’ risk

Class 3: ‘Low’ risk


MAXIMUM API INSPECTION INTERVALS (BY CLASS)

Type of circuit

Thickness measurements

External visual

Class 1 5 years 5 years



Injection points

3 years By class

S/A interfaces - By class


API 570 PIPING CLASSES

Class 1Flammable services/flash-off leading to brittle fractureExplosive vapours after flash-offH2S gaseous

Hydroflouric acidPiping over public roads



Class 2Most other process pipingOn-site hydrocarbonsH2, fuel gas and natural gas On-site acid and caustics



Class 3Fluids that will not

flash off (even if they are flammable)

Distillate/product storage/loading lines

Off-site acids and caustics


API 570 SUMMARY

•API 570 specifies the main points to look for

•Remember the pipe classes (and their inspection periods)

•Simple wall thickness determination

570

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