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API 570

PIPING INSPECTION

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API 570 Piping Inspection Code

570

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API 570 COVERS IN-SERVICE INSPECTION OF PIPING

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

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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

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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

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INJECTION POINTS

Why is particular inspection attention (and TMLs)needed at

injection points ?

….and what are TMLs anyway

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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’)

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API 570 INSPECTION METHODS

Internal

visuals

TMLs(4 quadrants)

Externalvisual

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DEADLEGS

Deadleg

Corrosion rates are higher

around deadlegs

Redundant deadlegs should be removed

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CORROSION UNDER INSULATION (CUI)

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CORROSION UNDER INSULATION (CUI)

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CORROSION UNDER INSULATION (CUI)

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CORROSION UNDER INSULATION (CUI)

Almost total wastage of bolts

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CORROSION UNDER INSULATION (CUI)

API identifies the areas that are most susceptible to CUI

Mist from cooling towers

Near steam ventsand deluge systems

Acid vapours

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•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 INSULATION (CUI)

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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

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SOIL/AIR INTERFACES

All interfaces without cathodic protection

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

insulation is damaged

CORROSION UNDER INSULATION (CUI)

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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%

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EROSION AND EROSION-CORROSION LOCATIONS

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

TMLS FOR EROSION/CORROSIONDownstream of ………..

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An example

EROSION/CORROSION

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Erosion/Corrosion after flow-restriction

features

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STRESS CORROSION

CRACKING (SCC)

Rule:In most circumstances,SCC is

due to

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SCC ON A GAS PIPELINE COMPONENT

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SCC ON A GAS PIPELINE COMPONENT

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What is this?

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API 570 GUIDE ON REPAIR PATCHES

D

Max D/2

Repair patch

Not permitted

25mm min radii

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API 570 GUIDE ON REPAIR PATCHES

Requires a full repair sleeve

Min 2D

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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

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MAXIMUM API INSPECTION INTERVALS (BY CLASS)

Type of circuit

Thickness measurements

External visual

Class 1 5 years 5 years

Class 2 10 years 5 years

Class 3 10 years 10 years

Injection points

3 years By class

S/A interfaces - By class

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API 570 PIPING CLASSES

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

Hydroflouric acidPiping over public roads

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API 570 PIPING CLASSES

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

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API 570 PIPING CLASSES

Class 3Fluids that will not

flash off (even if they are flammable)

Distillate/product storage/loading lines

Off-site acids and caustics

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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