Pipes Surface Preparation Inspection
From MarineWiki
Contents |
Introduction
The surface preparation is done on a pipe prior coating. It is usually done on carbon steel pipes only.
Purpose
The surface preparation inspection is done to verify that the condition of the pipe before coating is as per the standards, like SA 2.5. The surface, depending on the standards, must be free from rust, mill scale, oil etc. The profile of the surface must be evenly rough to enable the binding of the coating that is applied.
Depending on the material of the pipe and the subsequent coating there are various types of profiles.
Carbon Steel Pipes, Internally Coated with Polyethylene
These pipes are usually used in the sea water cooling line in engine room.
- Visual Check
- Surface Profile Thickness measurement
- Surface Comparator check
Condition
The pipes are laid out for ease of visual inspection.
Procedure
| Tests | ||
| Illustration | Description | Check Points |
|---|---|---|
 | Visual Inspection
The pipe coating is inspected visually for any damage to coating. |
|
   | Surface Profile Thickness measurement
The surface profile is measured by replica tape and plunger type dial gauge. Initially the replica tape is placed over the surface and pressure is applied so as to transfer the surface profile to the tape. After that the thickness of the profile is taken using the plunger type dial gauge. Once the original thickness of the tape is reduced from this value, we can get the thickness of the profile. In the above case, the surface is as per Sa 2.5 and it is checked whether the profile is in range of 50 - 90 micrometers. In the above snap the thickness of the tape is 50 micrometer. |
|
| Conclusion
The outcome of the test has to be noted down and any suggestion has to be mentioned in the inspection report. | ||
Common Defects
| Tests | ||
| Illustration | Description | |
|---|---|---|
 | Surface Cleaning
Sometimes grits and dust can be seen on pipe surface, which needs to be cleaned. | |
