Sunday, August 29, 2010

Re: [MW:6765] Re: What is SR(PWHT) thickness requirements by AWS D1.1

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.gmsrini@gmail.com> wrote:

From: Srinivas Engr <srinivas.gmsrini@gmail.com>
Subject: [MW:6758] Re: What is SR(PWHT) thickness requirements by AWS D1.1
To: "Materials & Welding" <materials-welding@googlegroups.com>
Date: Sunday, 29 August, 2010, 12:27 PM

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 Aug 28, 2:47 pm, Karthik <karthik6...@yahoo.com> wrote:
> 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.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" <materials-welding@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
>
> --
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For more options, visit this group's bolg at http://materials-welding.blogspot.com/
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