Vessel assesment of 60's multilayer vessel.

[trevornelson]

Hi all
I am looking for some advice on multi layered vessels. We use a 1964 multilayered vessel in our test facility for pressure testing in the UK. It does not present us any problems in day to day use however it is due for maintinance cleaning and repainting. I am considering having it inspected after blasting to ensure we have sufficient wall thickness etc , integrity etc. It is used daily but not up to its working pressure so would be quite happy to derate it if required.

My questions are on recomendations of inspections:
1. what would be the best method if inspection / NDT on a multi layered vessel?
2. Would it be worthwhile to recalculate the working capacity based on current codes?
3.Is there a service life on a vessel of this type if its well maintained?
4. Does anyone know the failure modes or where we should be concentrating our inspections.

We will be using local inspectors and engineers possibly someone like BV, Lloyds or equivalent. I have no experience in multilayer vessels however so doing my homework before I commission work to ensure we get worthwhile results from the activity.

The vessel is:
Chicargo Iron and Bridge Company. Horton Multi Layered Vessel, Ex- Methanol Converter 5200psi.33" ID and 53 ft long. Construction 1964.

Any advice would be appreciated.

Best wishes,
TN

 

[weldstan]

RT of welds. Visual examination for corrosion.

 

[TGS4]

Layered vessels have many damage mechanisms that are not detectable by any NDE/inspection technique.

You stated that it is being used daily, but not up to its working pressure. That says to me that this vessel is operating in cyclic service. Evaluation of layered vessels in cyclic service is a very special technical topic that requires expert-level engineers. I would recommend that you contact an expert.

 

[weldstan]

You should also do UT from the ID surface into the first layer weld and OD surface into the final layer. Seperation between the layers can initiate cracks. How many layers are there?

Good luck! As TGS4 rightly stated, some discontinuities cannot be found.

 

[r6155]

Try with Acoustic Emission Testing

Regards
r6155