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Up Topic Welding Industry / Technical Discussions / PWHT
- - By ekis (*) Date 05-13-2008 18:29
HI GOOD DAY PERHAPS YOU CAN HELP ME, iS VESSEL SKIRT (CIRCUMFERENTIAL SEAM WELD)UNDER ASME VIII DIV.1 MATERIAL IS A 516 GRADE 70 GROUP 1 TO 2 with a thickness of 16mm to 22mm require PWHT. THANKS!
Parent - - By js55 (*****) Date 05-13-2008 19:23
What's the MDMT?
Parent - By ekis (*) Date 05-13-2008 19:30
I dont have the vessels data right now, but could you tell me what is the MDMT range that require PWHT in connection to my previous question, please, thank u very much.
Parent - - By jon20013 (*****) Date 05-13-2008 19:39
Not sure the MDMT has any bearing on PWHT js55?  I've responded in one of the other threads (this person posted same question in about 3 threads...) that by memory, ASME VIII considers the lesser thickness in an unequal thickness joint (hope I haven't got this confused with preheat, don't have code at my home).  In any case, if adequate preheating equipment were available, a 200F preheat would negate need for PWHT.  This is just P1, Gr. 2 stuff, nothing exotic.  Usually any P1 material greater than 19mm would require PWHT unless exempted by elevated preheats.
Parent - - By ekis (*) Date 05-13-2008 19:45
Thanks for your reply, correct me if Im wrong what Im understand for thickness of 19mm which require PWHT is from ASME B 31.1, how about for Pressure Vessel under ASME Sec. VIII Div.1, I think PWHT requirements is under UCS 56, iM NOT ONLY SURE WHAT IS THE EXACT REQUIREMENTS FOR SA516 GR. 70 GRP 1 TO 2
Parent - - By jon20013 (*****) Date 05-13-2008 19:48
As I mentioned, 19mm is a "general" break off point for ASME in the P1 materials.  "Normally" anything greater than 19mm WOULD require PWHT.  SA516, Gr 70 is a P1 material and the PWHT tables will define REQUIREMENTS for PWHT based on material family, i.e., P1 AND thickness.
Parent - - By ekis (*) Date 05-13-2008 19:55
I see,  I understand that 19mm and above require PWHT for piping for P1 as per table 331.1.1 of ASME B31.3, is this requirement applies also to pressure vessel under ASME VIII DIV 1, THEY DO HAVE THE SAME CRITERIA WHEN IT COMES TO PWHT?
Parent - By jon20013 (*****) Date 05-13-2008 19:58
Ekis, as I mentioned in private message, nothing I say can negate what the code book says, you will have to pick it up and look at it for yourself.  Look to the PWHT Tables in UW and that will define for you the thickness based on material family at which PWHT becomes a REQUIREMENT.  My best guess, from being around ASME for some 25 years is you'll find 19mm is the point, but again, I'm writing from home and don't have the code book, you should have it.  Check it.
Parent - - By js55 (*****) Date 05-13-2008 19:46
jon,
Good Lord!!!! 
This is a case of severe cerebral rectumitis. :)
For whatever reason I had impact testing in my head. And my head in my,,,,,,
thanks
jon.
Parent - By js55 (*****) Date 05-13-2008 19:48
ekis,
I have two points of advice.
1) Section VIII Division 1, spend some time with it. A lot of time if your doing PV's.
2) Listen to jon.
Parent - - By jon20013 (*****) Date 05-13-2008 19:50
:)  Well, js55 that makes me feel better about my cerebral flatulence of the week prior.... I guess we all get a little gassy with age!  ;)
Parent - - By js55 (*****) Date 05-13-2008 20:57
ekis,
If you're doing PV's under Section VIII why are you talking about B31.3?
Section VIII Division 1 Table UCS 56. P-1 Groups 1, 2, and 3.
Read the notes, this is where jon gets the 200degF PH exception.
Parent - By ekis (*) Date 05-13-2008 21:14
Yeah your right JS 55, Just now I have a chance to read UCS 56,  a minimum Preheat temp. of 200 deg F should be apply during welding in lieu of PWHT for Thickness 1 1/4 to 1 1/2 in. for P1, P2 P3 materials, mandatory requirements for PWHT under Sec VIII Div. 1 is 1 1/4 for the above materials, lesser thickness applies only on lvessels containing ethal services as per UW 2 (UCS 56 C 1 TO 5) I am right js55? Thanks for your unending support anyway!!!
Parent - By ekis (*) Date 05-14-2008 08:31
Im talking ASME B31.3 because he mentioned of 19mm Thickness that require PWHT, which I believed this is a minimum nominal wall thickness that requires PWHT for P1 A1 as per Table 331.1.1 of ASME B31.3, My question to you most beloved and respectable Sir, Is this requirements applicable also to ASME VIII Div. 1?
does this two codes correlates to each other when it comes to PWHT? Thanks and more power to you!!!
Parent - - By new tito (***) Date 05-13-2008 21:56
Could I ask why you are only concerned with the skirt to shell weld? 

Was the vessel PWHT'ed and then the skirt need to be welded on, or is the vessel not thick enough to require PWHT, but you are concerned that the skirt is?  If it is the latter, as Jon mentioned, the skirt would not require PWHT if welded to a shell that did not originally require it.
Parent - - By ekis (*) Date 05-14-2008 10:17
I just asked for the skirt coz vessel main body with half skirt was shop pre-fabricated and the other part of the skirt together with the main body to be welded on site either on horizontal position or in vertical position of the vessel, Im not pretty sure if they have done PWHT at the shop, they submitted WPS without PWHT, a Skirt thickness is 20mm SA 516 GR 70 Grp 1 and to be joint welded to SA 283 GR C by double butt welded joint. Could you help me please coz Im not an Welding engineer or a metalurgical engineer and I have a little knowledge about welding Im just a Pipe fitter foreman utilized as Welding supervisor, I think that I will gain more knowledge in welding through this forum. More power.
Parent - - By new tito (***) Date 05-14-2008 13:04
I'm still having a hard time figuring out your explanation of the vessel configuration....

However, 1st thing I would do is contact the shop and ask them if the vessel - 1)requires PWHT; 2) if PWHT is required, find out if it has been before shipment.  I would start there.

On another note - this is a vessel, and it seems that ASME sec VIII is the applicable code.  B31.3 deals with process piping, and process piping only, not vessels.  Make sure not to get the two mixed up.  There should not be any instances where you would use any table in B31.3 to apply to anything in ASME sec VIII....unless it specifically references it, and I'm not aware of any paragraph where that occurs.
Parent - - By ekis (*) Date 05-15-2008 05:21
First of all I want to thank you with regards to your  concern to my question and I will give further explanation and hopefully this will clear your doubt, the vessel is a vertical vessel with a 4 m skirt, and have 3 courses and two circumferential double buttweld seam welded and the upper portion directly welded to the vessels bottom head, the two parts of the courses of the welded together in shop(one joint the top shell top portion welded directly to vessel bottom head and the other joint is the one joining the upper shell and middle shell and balance is the joint which joining the middle shell and bottom shell of the skirt),
Parent - - By js55 (*****) Date 05-15-2008 13:19
The requirements of B31.3 have nothing to do with the requirements of Section VIII. The project documents will determine what code you use. If it says VIII then it VIII.
Parent - By ekis (*) Date 05-16-2008 17:36
Exactly sir!
Up Topic Welding Industry / Technical Discussions / PWHT

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