What is SR(PWHT) thickness requirements by AWS D1.1

[Srinivas Engr]

Dear all,

what r thickness to be done for SR(PWHT) for CS according to AWS D1.1
structural steel code?
Where to refer in AWS D1.1? for thickness requirements for PWHT?

Thanks
Srinivas

[Karthik]

Hi Srinivas, Pls.refer to AWS D1.1-Section 5.8 for SR.Also Pls.find below the extraction of that.   5.8 Stress-Relief Heat Treatment Where required by the contract documents, welded assemblies shall be stress relieved by heat treating. Final machining after stress relieving shall be considered when needed to maintain dimensional tolerances. 5.8.1 Requirements. The stress-relief treatment shall conform to the following requirements: (1) The temperature of the furnace shall not exceed 600°F [315°C] at the time the welded assembly is placed in it. (2) Above 600°F, the rate of heating shall not be more than 400 °F per hour divided by the maximum metal thickness of the thicker part, in inches, but in no case more than 400°F per hour. Above 315°C, the rate of heating in °C/hr shall not exceed 5600 divided by the maximum metal thickness, in millimeters, but not more than 220°C/hr. During the heating period, variations in temperature throughout the portion of the part being heated shall be no greater than 250°F [140°C] within any 15 ft [5 m] interval of length. The rates of heating and cooling need not be less than 100°F [55°C] per hour. However, in all cases, consideration of closed chambers and complex structures may indicate reduced rates of heating and cooling to avoid structural damage due to excessive thermal gradients. (3) After a maximum temperature of 1100°F [600°C] is reached on quenched and tempered steels, or a mean temperature range between 1100°F and 1200°F [600°C and 650°C] is reached on other steels, the temperature of the assembly shall be held within the specified limits for a time not less than specified in Table 5.2, based on weld thickness. When the specified stress relief is for dimensional stability, the holding time shall be not less than specified in Table 5.2, based on the thickness of the thicker part. During the holding period there shall be no difference greater than 150°F [85°C] between the highest and lowest temperature throughout the portion of the assembly being heated. (4) Above 600°F [315°C], cooling shall be done in a closed furnace or cooling chamber at a rate no greater than 500°F [260°C] per hour divided by the maximum metal thickness of the thicker part in inches, but in no case more than 500°F [260°C] per hour. From 600°F [315°C], the assembly may be cooled in still air. 5.8.2 Alternative PWHT. Alternatively, when it is impractical to PWHT to the temperature limitations stated in 5.8.1, welded assemblies may be stress-relieved at lower temperatures for longer periods of time, as given in Table 5.3. 5.8.3 Steels Not Recommended for PWHT. Stress relieving of weldments of ASTM A 514, ASTM A 517, ASTM A 709 Grades 100 (690) and 100W (690W), and ASTM A 710 steels is not generally recommended. Stress relieving may be necessary for those applications where weldments shall be required to retain dimensional stability during machining or where stress corrosion may be involved, neither condition being unique to weldments involving ASTM A 514, ASTM A 517, ASTM A 709 Grades 100 (690) and 100W (690W), and ASTM A 710 steels. However, the results of notch toughness tests have shown that PWHT may actually impair weld metal and HAZ toughness, and intergranular cracking may sometimes occur in the grain-coarsened region of the weld HAZ.   Thanks & Regards,   (Karthik) Karthikeyan.S QA/QC Manager Getabec Energy Co.,Ltd. 379,Moo6,Soi8,Nikhomphatana, Rayong-21180, Thailand. Phone: 0066 38 897035-8 (Off) Fax: 0066 38 897034 Hand Phone: 0066 892512282 --- On Sat, 8/28/10, Srinivas Engr <srinivas...@gmail.com> wrote:

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[Srinivas Engr]

Dear Karthik,

section 5.8 is ok.
What i am asking is for a 30 mm CS plate is my job,?
where i to refer this thickness of CS plate either has to be done for
SR or not in AWS D1.1?
In asme b31.3 there is one chart is for Piping tat for cs >20mm we
have to do PWHT?
Like tat any chart is available in AWS D1.1 or not?
Either how can we refer for thickness? by AWS D1.1
Pl clear me...........


Thanks

> --- On Sat, 8/28/10, Srinivas Engr <srinivas.gmsr...@gmail.com> wrote:

>
> From: Srinivas Engr <srinivas.gmsr...@gmail.com>
> Subject: [MW:6753] What is SR(PWHT) thickness requirements by AWS D1.1
> To: "Materials & Welding" <material...@googlegroups.com>
> Date: Saturday, August 28, 2010, 11:46 AM
>
> Dear all,
>
> what r thickness to be done for SR(PWHT) for CS according to AWS D1.1
> structural steel code?
> Where to refer in AWS D1.1? for thickness requirements for PWHT?
>
> Thanks
> Srinivas
>
> --
> To post to this group, send email to material...@googlegroups.com
> To unsubscribe from this group, send email to materials-weld...@googlegroups.com

> For more options, visit this group's bolg athttp://materials-welding.blogspot.com/

[kannayeram gnanapandithan]

Not like  construction codes like asme sec1, 8 ect on Thickness restriction for PWHT, in AWS there is no set rules on thickness, but it is ur requirement like in  ASME sec IX( applicable or not)

kgp

For more options, visit this group's bolg at http://materials-welding.blogspot.com/

[GURDEEPSINGH ARORA]

Dear   Norsok standard M-CR-101 gives the following guideline: 7.11 Post weld heat treatment (PWHT) PWHT shall be required for structural welds assigned design class 1 when the nominal thickness (as defined in EN 288-3, section 8.3.2.1) exceeds 50 mm, unless adequate fracture toughness can be documented in the as welded conditions. For restrained joints of complicated design, PWHT may be required for smaller thicknesses, independent of design class. PWHT shall be carried out in accordance with a procedure specification which shall include: The holding temperature shall be as recommended by the steel manufacturer. The holding time shall be 2.5 min per mm thickness. The temperature difference between different parts of the structure during soaking time shall not exceed 30 °C within the heated area. Double sided heating shall be used as far as possible. The temperatures shall be continuously and automatically recorded on a chart. G.S.Arora B4-103 LaHabitat Opp Marutinandan Villa Near Aayna Shopping Complex Off SG Road Thaltej AHMEDABAD-380054 Ph: 91-9725262404

--- On Sun, 29/8/10, Srinivas Engr <srinivas...@gmail.com> wrote:

For more options, visit this group's bolg at http://materials-welding.blogspot.com/

[Safa Özhan]

Dear All,

I think we've got a really serious problem regarding PWHT of dissimilar
materials.

In some of our in-house applications, we have to weld hydro test caps on
open ends' of pipe-spools in order to hydro test them.
After welding of caps are completed, we heat treat the spools together with
(most of the time caps made of dissimilar material, mostly CS Caps because
of cheapness) Hydro-Test caps. Even though, thickness of these hydro test
caps are calculated as per related code, one of our concern starts because
of the effects of excessive heat treatment on hydro test caps. Because; as
per codes, allowable stress values should be chosen in accordance with the
hydro test temperature which should be lower because of excessive PWHT, but
how much ? Are there any codes explaining this situation ? Does any member
has experienced same kind of problem ?

Other concerning point is the service life of that work piece. Even though
the caps work properly after PWHT, then the question should be how many
times we can use that caps in our other hydro tests, of course safely.

The main problem indeed is, are there any approach which can assume/predict
the material properties (Especially reduction in durability.) after PWHT
depending of PWHT parameters ?

It would be highly appreciated if some of you can address a code with a
working example of solution.

In order to visualize the problem pls see below example of the concerning
situation;

- Material of spool is P91 and the cap's is CS.
- PWHT temp : 730 C
- PWHT duration : 1 hr.

How can we calculate the reduction in durability ?

Thanks for your time,

Regards,

Safa

[Johnson Madukayil]

Why do you have to keep the hydrotest caps on after hydrotest? I would advise you to remove the caps and then do the PWHT.

Johnson Madukayil

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[Karthik]

Hi, There is no thickness requirement for PWHT mentionede in AWS D1.1.But it specifies "Where required by the contract documents, welded assemblies

> shall be stress relieved by heat treating."

If there is any reqirement by the customer,PWHT need to be done as per 5.8 of AWS D1.1 .regardless of thickness. Also pls.refer C3.14 of AWS D1.1 Thanks & Regards,   (karthik)

Karthikeyan.S QA/QC Manager Getabec Energy Co.,Ltd. 379,Moo6,Soi8,Nikhomphatana, Rayong-21180, Thailand. Phone: 0066 38 897035-8 (Off) Fax: 0066 38 897034 Hand Phone: 0066 892512282

--- On Sun, 8/29/10, Srinivas Engr <srinivas...@gmail.com> wrote:

For more options, visit this group's bolg at http://materials-welding.blogspot.com/

[Safa Özhan]

Dear John,

 

Thanks for your reply, but as per our design codes PWHT should be done before Hydrostatic test.

 

Safa

[Karthik]

Hi, You can do PWHT before hyrotest without caps by add(200 to 300mm) small length of same P91 pipe to the existing pipe spool .After PWHT, you can weld the hydrotest cap to the end of added pipe length. After Hydrostest finished you cut the excess length of the pipe with cap. This will be the best one,if you concern about the caps durability.

Thanks & Regards,   (karthik)  Karthikeyan.S QA/QC Manager Getabec Energy Co.,Ltd. 379,Moo6,Soi8,Nikhomphatana, Rayong-21180, Thailand. Phone: 0066 38 897035-8 (Off) Fax: 0066 38 897034 Hand Phone: 0066 892512282

--- On Mon, 8/30/10, Safa Özhan <safa...@gmail.com> wrote:

[Johnson Madukayil]

Does this also imply that there will be no field hydrotest afterwards?

Johnson Madukayil

[Safa Özhan]

Dear Johnson,

 

There will be no field hydrotest afterwards.

 

Regards,

 

Safa

 

From: material...@googlegroups.com [mailto:material...@googlegroups.com] On Behalf Of Johnson Madukayil

Sent: Monday, August 30, 2010 12:33 PM
To: material...@googlegroups.com