PWHT temperature for Amine Service

[jtseng123]

Dear all,

Our metallurgist recently accepted a amine service vessel PWHT'ed at 1140F -1155F, saying it met code Table UCS 56-1 of 1100F minimum and also hardness was within 200 BHN such that API RP 582 asking PWHT at 1150F-1200F does not need to follow.

Any thought ?

 

[DVWE]

The key to API RP 582 is "RP": Recommended Practice.

I agree with your metallurgist unless this document was mandated by contract between you and your client.

 

[metengr]

Agreed from another metallurgist's perspective.

 

[pradipgoswami]

Hi jtseng123,

Here are the snapshots of various API documents related to Amine service:-

RP-582-Material carbon steel-all thickness-anime service- Holding Temperature-1150 to 1200 Deg C- Holding Rate 1 hr/in.-Nominal Holding Temperature1hr minimum).

API RECOMMENDED PRACTICE 945-Avoiding Environmental Cracking in Amine Units:- An effective procedure consists of heating to 593--649 deg C(1100 -1200 deg F) and holding in this temperature range for 1 hour per 25 mm (1 in.) of metal thickness, or fraction thereof, with a 1-hour minimum holding time.

Usually API RP-945 is mandatory document in addition to ASME code, by today's technical requirements for construction of new anime plant equipment.

RP-582 applies to welding requirements only.It does not mandate additional design requirements as API-RP-945 does for design, fabrication of new anime equipments.

The PWHT temperature range adopted by the fabricator is closer to the PWHT Temp of API-RP-945. Please check if the nominal holding time(1Hr minimum) was followed or not. If done so then technically it should be fine.

Also please check if RP-945 is a requirement of the contract.If not done, you do so retrospectively also, or else you may have have problems later in post commissioning operations and weld repairs. The reason being simple, the repair contractor may follow the ASME Sec VIII guidelines and walk away.

Thanks.

Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
Ontario,Canada.
ca.linkedin.com/pub/pradip-goswami/5/985/299
All provided answer are personal opinions or personal judgements only. It's not connected with any employers by any means.

 

[jtseng123]

Pradip,

RP-945 is not in the contract. RP-582 is. Holding time is one hour min. per code. Thanks for your opinion.