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SHELL DEP Material restriction

SHELL DEP Material restriction

SHELL DEP Material restriction

Hello All,
(AMENDMENTS AND SUPPLEMENTS TO ISO 15156:2009amendment for ISO 15156) noticed that more environmental restrictions are imposed.On Table A.2 its mentioned that UNS 20910(Nitronic 50) the max allowed temperature is only 66 degC and the allowed H2S partial pressure is 100 kpa.
The allowed temperature is much lower to SS316L(149 degC).Actually the UNS 20910 is better MOC and harder than SS316L.
Moreover for valves its mostly used as Shaft/stem.In ISO 15156 there is a Table A.3 for shaft,stem and pin and it allows UNS 20910 without any restriction.
How these two valid standards be so contrary.Moreover presume that temperature mentioned as Max is only the operating and not the design condition.Please clarify.

RE: SHELL DEP Material restriction

The same issue has come to me while working with these standards however no final conclusion was reached. I can not technically answer for this ambiguity but I can tell you what we follow -

XM-19 has been recommended by a lot of vendors for valves and shafts and have been used for many years in clients facility with no known issues.

Since DEP restricts it, client has advised us to stop using the same for new projects.

RE: SHELL DEP Material restriction

1. The subject DEP is now withdrawn
2. Some materials have a more restrictive set of environmental variable limits; some have a more relaxed set.
3. The environmental variable limits have been set using an extensive databank of Shell and third party test results
4. Shell's general philosophy is not to entertain ISO 15156-3 tables that contain no environmental variable limits as is the case with Table A.3
5. The environmental variable limits are as given in Table A.2.
6. In using the Shell DEP, the temperature will be the design temperature on the basis that SSC/SCC may occur extremely rapidly should the environmental variable limits be breached. Thus, even a transient excursion to the design temperature may have unacceptable consequences.
7. Item 6 necessitates a clear definition of design temperature and that is given in DEP which you should also be using.

Steve Jones
Corrosion Management Consultant


All answers are personal opinions only and are in no way connected with any employer.

RE: SHELL DEP Material restriction

Thanks steve.
Sorry,self not aware that this DEP is now withdrawn.
so what it been replaced with.Is that replaced one has relaxation on MOC.please advice.


RE: SHELL DEP Material restriction

The subject DEP has now been subsumed into DEP

Steve Jones
Corrosion Management Consultant


All answers are personal opinions only and are in no way connected with any employer.

RE: SHELL DEP Material restriction

I would like to add that shell valve datasheet for higher design temperature itself allows the use of XM-19.

Example: Check class 13461 - Butterfly Valve

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