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Thickness Selection for CVN Qualification

Thickness Selection for CVN Qualification

Postby laurudolphy » Thu Jan 02, 2014 12:09 pm

HI, Weldinguide Folks,

For the purpose of brain storming, I have the following query and I would request some advise, preferably with references, if not please give me just your opinion.

I have a 25 mm thickness EH36 material (Group 2) plate coupon welded in CJP (complete joint penetration) butt weld using 3G position. The mechanical tests, in terms of hardness, bend test, etc. have all passed (that qualification was done 5 years ago). As per AWS D1.1 that procedure qualification qualifies for:-
Thickness = 3 mm to unlimited.
Material = Group II to Group II, Group II to Group I, Group I to Group I.
Pipe Diameter = 600 mm and above.
Position = F and V.

Currently, I would like to extend this WPS for a job where IMPACT TEST is a requirement. Please advise me on the following:
1. What is the thickness of the plate that I should use for welding a new coupon ONLY for CVN Testing.
2. Number of coupons that I should prepare.
3. What is the position that I should weld this coupon.
4. What is the material that I should choose. Should it be material from group II or group I.
5. Can I weld 2 coupons, one coupon by Group I and another by Group II.
6. By welding 2 coupons as mentioned in point 5 above, can I club the 2 reports and say that the WPS is valid for Group II and Group I.
7. With the suggested thickness for coupon of Point 1 above, what would the qualified thickness range be.

Your input will be highly appreciated.

Thanks/Regards
laurudolphy
 
Posts: 51
Joined: Wed Aug 14, 2013 1:19 pm

Re: Thickness Selection for CVN Qualification

Postby mawsamit » Fri Jan 10, 2014 5:46 pm

Hi Laurudolphy,
Please see below my replies to your queries:

Laurudolphy wrote:As per AWS D1.1 that procedure qualification qualifies for: Position = F and V.
As per table 4.1 that procedure qualification qualifies only for position V (not for F).
Laurudolphy wrote:1. What is the thickness of the plate that I should use for welding a new coupon ONLY for CVN Testing.
As per clause 4.36.3 and the variable 2 of table 4.6, you should weld the thinner plate that is available to you so as to qualify for the greater range regarding material thickness.
Laurudolphy wrote:2. Number of coupons that I should prepare.
I think one test coupon is enough.
Laurudolphy wrote:3. What is the position that I should weld this coupon.
I suggest you weld on vertical up position so as to qualify for all positions regarding CVN test requirements (please have a look at variable 6 of table 4.6)
Laurudolphy wrote:4. What is the material that I should choose. Should it be material from group II or group I.
You shall use Group II material (please have a look at variable 1 of table 4.6).
Laurudolphy wrote:5. Can I weld 2 coupons, one coupon by Group I and another by Group II.
Yes, you could weld both Group I and Group II materials so as to prepare two test coupons and qualify for both Groups.
Laurudolphy wrote:6. By welding 2 coupons as mentioned in point 5 above, can I club the 2 reports and say that the WPS is valid for Group II and Group I.
Since the WPS is to give specific instructions to the welder, it cannot specifies two different materials. So, even the existing PQR can be extended by welding group I and/or Group II material(s), the WPS shall always specify a single material. That means the number of WPS that you have to prepare is equal to the number of different materials that you are to weld.
Laurudolphy wrote:7. With the suggested thickness for coupon of Point 1 above, what would the qualified thickness range be.
For the thickness range qualification, please have a look at variable 2 of table 4.6.

regards,
mawsamit
mawsamit
 
Posts: 28
Joined: Thu Oct 24, 2013 11:16 am

Re: Thickness Selection for CVN Qualification

Postby Logosweld » Tue Jun 10, 2014 9:39 am

The thickness combination especially the T1 (Bevelled) will be selected in other to cover the thickness ranges in production. If the project specification refers you to AWS D1.1 code as a reference code without additional conditions, then refer to AWS D1.1 table 4.2 for your thickness selection. Using the standard pipe 8” sch. 80/sch. 140 (refer to figure 4.27) will qualify tubular diameter of 4” and above with thickness of 5mm to unlimited, but i know that your client specification might over ride this clause. Note that the thickness selected has little to do with the impact property but rather, your choice of consumable and the welding parameters will greatly influence the Impact values. AWS D1.1 clause 5.8 state that PWHT shall be carried out when required by contract document and clause 3.14 (2) stated that PWHT shall not be carried out on TMCP materials.

Note also that according to API 2W paragraph 1.2 stated “Due to the inherent characteristic of TMCP method, plates manufactured to this spec cannot be form or Post weld heat treated at temperatures above 1100°F (595°C) without some risk of sustaining irreversible and significant losses in strength and toughness”.

YES, this qualification will qualify welding on API 2MT1 gr. 50 because, they are both in the same group AWS D1.1 table 3.1 and their delivery condition is the same (TMCP). Both also have same weldability.

Yes you can use a lower thickness. Note that according to ASME sec IX, the weld metal thickness t deposited during qualification qualified for 2t in production.
Logosweld
 
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Location: India


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