Normalising requirment

[sachin sankhe]

Hi,

As we all aware that ASME Sec VIII Div.1 do not speak on normalising requirement
Then when we say Normalising is done at 910 Deg.C and with holding time as 1mm/min, then what is the basis for the same.I mean acceptence code

Futher to this ASME Sec VIII Div1 says that if due to cold forming fibre elengoation is more than 5% then heat tretment as per UCS 56 to be done.However most of the client spec mention that normalising need to be carried out.
I feel that for small thk say 12-13 mm normalising is not appropriate and may warp the matereial.So in that case can we accept stress relieving?
In EIL spec normalising is mentioned above 16 mm if fibre elongation is more than 5%

Request you to clarify above query giving reference of code


Regards
Sachin
Regards
Sachin.Sankhe

[hegd...@isgec.com]

As far as normlizing is concern
C ode is silent
Incase of dished end. Normalizing is recomended (for fibre elongation above 5 per ) to recrestalise the grain strucure. Perticularly for higher thk above 16mm
.However soaking time depends upon thk of plate where it is essential for complete phase transformation ( austenite)for through thk.
Also higher soaking time causes grain growth. Causes deteoration in uts which also depends upon chemistry of plate

) Its soaking time depends upon the mill recomendation ( given in tc) and plate thickness and simulation asked by fabricator for perticular plate w r t desire mech properties
on this basis mill produce the plate
Also soaking time to be given by fabricator is based on experience obtain by various simulation of MTC after normaliing verses test results
Higher soking time causes deteoration in UTS so soking time for CS plate is recomeded between 0.8 to 1 min per mm. To get adequet mech properties

CS Plate less than 16mm can be stress relieved if it is not HIC requirement

Regards
Hegde

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From: "sachin sankhe" <sachin...@rediffmail.com>

Sender: material...@googlegroups.com

Date: 22 Oct 2010 15:49:14 -0000

To: materials_welding<material...@googlegroups.com>

ReplyTo: material...@googlegroups.com

Subject: [MW:7718] Normalising requirment

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[pgoswami]

 
Sachin,
 
As per UCS-79-  Vessel shell sections, heads, and other pressure boundary parts of carbon and low alloy steel plates fabricated by cold forming shall be heat treated subsequently (see UCS-56) when the resulting extreme fibre elongation is more than 5% from the as-rolled condition and any of the following conditions exist i.e.  thickness of the part before cold forming exceeds 5⁄8 in. (16 mm).

 
By default ASME Sec VIII, DIV-1 code recommends Stress Relieving as post forming heat treatment also by NACE MR-0103-2007). For certain services, especially for wet H2S environments in refining and other sour environments, based on client (oil refiner's experience) heads should be fully normalized followed by SR (which would be performed while PWHT the whole vessel). My feel is this requirement is to :-

*               nullify any localized residual stresses, which may generate during excessive forming
*               cause uniformity of grain size and improve mechanical properties

I've come across this (NR) requirement in many oil clients' spec in the past. If you get hold of Shell's spec:- DEP 31.22.20.31-Gen.- Pressure Vessels (Based on ASME Section VIII) specifies: clearly:-

*               All parts which have been cold formed by more than 5 % shall be subjected to an appropriate normalizing treatment and, if necessary, a tempering treatment.

*               Normalizing of carbon steel components and base materials shall be performed separately and not as part of hot-forming operations, unless the finishing hot-forming temperature is in the normalizing temperature range of 850 °C (1560 °F) to 960 °C (1760 °F).

       
As EIL have pioneered many refinery construction and engineering in India for many years, they also incorporated this requirement in their specification 6-12-0002.I would guess that the cut off requirement of 16mm (5/8")  comes from SecVIII, DIV-1 cut-off criteria.

 
Dished heads below 16 mm(5/8") may be subjected to SR, unless specifically asked by client (oil refiner).
 
Thanks.

 
Pradip Goswami,P.Eng.
Welding & Metallurgical Specialist & Consultant
Email-pgos...@sympatico.ca,
pgos...@quickclic.net
 

________________________________

Regards
Sachin
Regards
Sachin.Sankhe
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[Varun Vvp]

gents,

With reference to normalising of dish end, how do i select the parameters? wiz heating rate and holding time??

Any reference? I cannot find any in ASME sec 8. Please help

On Friday, October 22, 2010 at 8:44:17 PM UTC+4, hegd...@isgec.com wrote:

As far as normlizing is concern
C ode is silent
Incase of dished end. Normalizing is recomended (for fibre elongation above 5 per ) to recrestalise the grain strucure. Perticularly for higher thk above 16mm
.However soaking time depends upon thk of plate where it is essential for complete phase transformation ( austenite)for through thk.
Also higher soaking time causes grain growth. Causes deteoration in uts which also depends upon chemistry of plate

) Its soaking time depends upon the mill recomendation ( given in tc) and plate thickness and simulation asked by fabricator for perticular plate w r t desire mech properties
on this basis mill produce the plate
Also soaking time to be given by fabricator is based on experience obtain by various simulation of MTC after normaliing verses test results
Higher soking time causes deteoration in UTS so soking time for CS plate is recomeded between 0.8 to 1 min per mm. To get adequet mech properties

CS Plate less than 16mm can be stress relieved if it is not HIC requirement

Regards
Hegde

Sent from my BlackBerry® smartphone from !DEA

---

From: "sachin sankhe" <sachin...@rediffmail.com>

Sender: material...@googlegroups.com

Date: 22 Oct 2010 15:49:14 -0000

To: materials_welding<materials-wel...@googlegroups.com>

[Chetan Kapadia]

Dear All,

Normalizing is specified at the discretion of the designer OR customer specification for basic reason of acheving thr Dished end properties after forming equal to the specified 

material properties.

In case of Normalizing following to be taken care:

CASE A:

(No welding is provided in the formation of dished end)

1. Placement of equivalent material test coupon for Normalising with dished end (which has been bent along with Dished end to equal to one which Dished end has under gone.)

2. This test coupon has to under go atleast tensile test & results are expected to meet 

specified minimum value of MOC. 

CASE B:

(Where welding of ground joint is carried out prior to forming & Normalizing as specified in approved  design & drawing)

1. First qualify WPS as per ASME SEC.IX  with weld coupon involving Normalizing before start of the fabrication activities.

2. Now like above part 2 in case 1 put welded test coupon & test as per ASME SEC IX. Additional test coupon of plate material bent to equivalent percentage of dished end percentage elongation may be provided.

Complete testing as per parent MOC specification. 

Special Note: Following to be taken care:

1. At time MOC requires impact test as well.

2. For LAS MOC requires post weld heat maintenance.

3. Due to 2nd Normalising of original plate material it is observed that UTS value reduces. by 5 Kg/cm2 & hence at the ordering stage of plates at plate mill simulation test pieces for Normalising & for weld test coupon is added as additional requirements over &  above specification requirenents. 

Also additional plate coupons are ordered to carry out Material testing during fabrication as discussed above. 

Hence above is conclusion on the subject matter. The codes are minimum requirements & guidance but engineering judgement is left to the fabricator & customer who are following the construction codes. This notes are in forward of all standards, specifications & 

code books.

Thanks & Regards,
C.B.Kapadia,
9892633442

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