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RE: [MW:25461] RE: 25392] PWHT

By Materials & Welding

There is a danger that the discussion is getting confused. Confirming what Ahmed Eissa wrote:

 

Hydrogen induced cracking (HIC) – using this term strictly in relation to the behaviour of carbon and carbon-manganese controlled rolled steels to crack where the process fluids contain relatively small quantities of hydrogen sulphide (and not the many other types of cracking related to hydrogen in steels) is unrelated to hardness. It is due to the presence of elongated manganese sulphide inclusions in the steel (type II manganese sulphide inclusions) which provide sites for the accumulation of atomic hydrogen which then form molecular hydrogen which fractures the steel, causing cracking or blistering.

 

Sulphide stress corrosion cracking of steels is again due to hydrogen sulphide and the factors are the concentration of hydrogen sulphide (partial pressure thereof) the pH of the solution and the susceptibility of the material, commonly assessed by its hardness. NACE MR0175 relates to this type of cracking.

 

Alan Denney

AKD Materials Consulting Ltd

From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of George Dilintas
Sent: 27 September 2016 08:12
To: Meghanadh K <materials-welding@googlegroups.com>
Subject: Re: [MW:25457] RE: 25392] PWHT

 

It is controlled by the crystalline structure and more specifically:

  1. by the diffusion of atomic hydrogen
  2. by the capability to sustain the pressure of molecular hydrogen by plastic transformation

The increase of hardness is an indication of low ductility and thus less possibility of plastic transformation of the grains

 

2016-09-26 19:25 GMT+03:00 'Ahmed Eissa' via Materials & Welding <materials-welding@googlegroups.com>:


Regarding the belowmentioned

I need to confirm that HIC is not controlled by hardness control but by steel chemistry 

 

All shall be reminded that wet sour service induce 

 

Sulfide stress cracking

Hydrogen induced cracking 

Stress oriented hydrogen induced cracking 

Hydrogen blistering 

 

Nace MR 0175 or nace MR 0103 only control ssc, please read these code introduction /preface 

 

Ahmed eissa 

Materials and Corrosion Engineer 

 

 

 

 

On Thu, 15 Sep, 2016 at 5:38 am, pgoswami

Hello, ZHY370137,

 

I'm not sure why you're asking this question is general forum, when your contract is bound by your clients' specifications and project requirements. Aramco has very comprehensive specifications for almost everything. If Aramco SAES-W-012 is applicable for your project you need to what's needed as per this spec.

 

What's  the design code, of the pipeline B-31.4 or 31.8? And what're the Aramco specifications applicable?

 

Usually for sour service hardness control is "mandatory" to mitigate the HIC. One of the effective ways to ensure hardness control is PWHT, unless vendor is able to prove otherwise.

 

Appreciate your response.

 

Thanks.

 

 

 

Pradip Goswami, P.Eng,IWE

Welding & Metallurgical Engineering Specialist ,
Ontario,Canada.
ca.linkedin.com/pub/pradip-goswami/5/985/299

pgoswami@quickclic.net

pradip.goswami@gmail.com

 

From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of zhy370137@gmail.com
Sent: Wednesday, September 14, 2016 10:59 AM
To: Materials & Welding
Subject: [MW:25392] PWHT

 

Dear sir

good day 

pls hlep us confirm whether we need apply PWHT for every girth weld according to your experience.

pipe ：API 5 L X60 HIC resistant pipe

welding method: CRC automatic

pipeline diameter and thickness:20inch 0.4inch(10MM)

medium：sour condensate 

pressure:960psi

pipeline distance：164km between two gas plant in saudi （safaniya plant to berris gas plant)

client：saudi aramco

 

CNPC daqing saudi 

QAQC

 

 

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--

Dr. Georgios Dilintas,

Dipl. Ing. In Aeronautic and Space Engineering

Ph.D in Mechanics of Solids - Computational Mechanics

A.I.S, A.N.I, IRCA Lead Auditor

Welding, Stress Analysis, Corrosion, QA/QC, Failure Analysis, Risk Analysis

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