GN 013 - Types of PE Signs or Indications

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Category: Use & In-Service Inspection

 

APEK
- AICIP
GUIDANCE NOTE

TYPES OF PE SIGNS OR INDICATIONS

 APEK GN 013
Rev 1
Issued: 22/04/2014

Developed for: ACA, AICIP, AIES, AINDT, CAAA, Eng Aust, Met. Aust, NATA, Stds Aust, WTIA, & PE Industry & Regulators

1   Scope

This Note lists various types of signs (unusual, abnormal or unexpected appearance, features, indications, imperfections (flaws), defects, damage, condition, deficiencies, or wrong or missing items, nameplates, marks etc) which may be observed mainly by visual inspection (VT) in pressure equipment (PE) and be present in original material, during manufacture, on initial supply or occur in-service.

Some definitions of particular signs have been included [in brackets] for trial. For others, see relevant material and product standards.

This note and its various cases provide some guidance on the occurrence, location and detection. See other documents re further details e.g. Ref 1 i.e. safe access, lighting, cleaning, viewing aids (boroscopes etc.)

 

2   Purpose

See relevant material and product standards etc.

Listed terms are preferred for use in various cases.

 

3   Types

Most signs can be grouped under the following headings:

 a) Cracks

 b) Suspect Material Thickness

 c) Suspect Shape, Form or Alignment (with Negligible Material Change)

 d) Missing or Wrong (or Unauthorised) Parts, Welds or Marks

 e) Suspect Surface Finish and Roughness

 f)  Suspect Material Properties (except for colour, usually not detected by VT)

 g) Suspect Material Colour

 h) Surface Scale, Deposits and Blockage

 i)  Suspect Coatings

 j)  Abnormal Movement

 k) Leaks

 l)  Suspect Noise, Smell, Feel and Taste

m) Combination of Signs

Individual signs are given in the following sections with definitions in [brackets].

 

4   Cracks

[crack split or rift in material (rupture or tear through material)].

Ductile fracture (shear or plastic instability); fatigue, creep; SCC; original weld cracks of various types, brittle fracture; sustained load cracks.

Crack-like signs include laminations. [Layering of material within the PE wall appearing as a discontinuity]; laps; laminar tearing; delamination (in plastics), and in weld lack of fusion or penetration and overlap, cut or scratch that leaves a sharp impression where material has been broken or partly removed.

 

5   Suspect Material Thickness

  • Corrosion (see Ref 1 for types); general, line, pit.
  • Erosion; abrasion; gouges; grinding mark; torn tack weld.
  • Incorrect holes e.g. power nail hole when packing aluminium HEX.

 

6   Suspect Shape, Form or Alignment (with negligible material change)

  • Dents [a butt impression depression in a part that has neither penetrated nor removed material].
  • Bulges [a swelling of part with little loss of material].
  • Blisters
    in steel plate with internal laminar hydrogen cracks
    in coating with corrosion of base metal
  • Distortion; bruise; hammer mark.
  • PE tilting (foundations settled), pipe sagging or not sloped properly.
  • Buckling
  • Incorrect dished end shape.

 

7   Missing or Unauthorised Parts, Welds or Marks

  • Insufficient inspection access; lack of vent or telltale hole; missing pipes
  • Missing or lost bolting or nameplates, welds, pipe hangers;
  • Hidden wrong weld repairs e.g. hole in wrong place; added nozzle or attachment.

 

8   Suspect Surface Finish and Roughness

Sharp corners, flame cut holes; incorrect flange face grooves; fins, burrs ____ or lips; fused electrode; wrong stainless steel surface finish (see Fig ???).

 

9   Suspect Material Type and Properties

  • Type may be detected by colour, rust, weight, magnetic or PMI etc;
  • Usually not detected by VT, but by inferred from other signs or by replication or micro examination.

 

10   Suspect Material Colour

  • Possibly very light, thin corrosion or staining - may suggest wrong material or high temperature (e.g. heat tint or signs of welding).
  • Incorrect colour e.g. green paint, rusty dark colour on LPG vessel (may de unacceptable aesthetically). Incorrect piping colour code.

 

11   Surface Deposits or Blockage (i.e. added material)

  • Sludge, oil, grease, product build-up, foreign materials (waste, rubbish, debris), scale, unwanted paint or crayon.
  • Dirty surfaces.
  • Weld spatter.
  • Seized parts (bolting).
  • Ice on cryogenic equipment (may indicate leak).
  • Paint blocking tell-tale hole (submarine lost for this).
  • Paint on crack contributed to bridge failure.

 

12   Suspect Coatings

  • Flawed paint, surface coatings, refractory, insulation, shielding.
  • Failure modes (may include defective aesthetics, defective hygienic quality.)

 

13   Suspect Movement

Vibration, expansion or contraction engagement e.g. sagging on QA door causing interference, gaps or loss of contact or engagement.

 

14   Leaks

Leak [Unwanted loss or gain of contents e.g. gas leak or vacuum leak].

 

15   Suspect Noise, Smell, Feel and Taste

Water hammer; loose baffle etc, (may indicate leakage); overheating; contamination; smell caused by microbial corrosion (MIC) etc.

Combination of Signs e.g.

  • Crack and Leak
  • Fire damage due to excessive general or localised heating of a PE usually indicated by:
  • charring or burning of paint or insulation.
  • fire damage of the material.
  • bulging or distortion of parts.
  • melting of metallic or plastic parts e.g. valve, instruments, gaskets, plug or cap.
  • Arc or torch burns (arc strikes) burning or melting of PE material, a hardened heat-affected zone, the addition of extraneous weld metal, or the removal of metal by scarfing or cratering.
  • Gouge and dent (Dangerous combination – see Case A04).
  • Impact damage.

 

16   Main Suspect Signs (Flaws or Imperfections) in PE Materials

 .1   In Plate, Pipe, Forging

Bursts, inclusions, laminations, laps, seams.

 .2   In Welds

Burn through; cracks; excessive/inadequate reinforcement; inclusions (slag/Tungsten); lack of fusions; lack of penetration; misalignment; overlap; porosity; root concavity; undercut.

 .3   In Castings

  • Rough Surfaces; hot tears or cracks;
  • Shrinkage; voids;
  • Non-metallic inclusions;
  • Gas porosity;
  • Veins, rat tails, scabs;
  • Fusion discontinuities: wrinkles; laps, folds, cold shuts and misrun.
  • Dressing marks: flame cuts, gouging grinding
  • Unfused inserts: chaplets, internal chills
  • External chills;
  • Fins.

 .4   In Gas Cylinders

 

17   References

See AS 2337.1 for metal gas cylinders

See AS 2337.3 for fibre reinforced plastics (FRP) gas cylinders.