If the misalignment between the head and shell in a pressure vessel exceeds the ASME requirements, what remedial action could be taken?
Kevin S. Mechanical fix Equipment Engineer at ISISAN During the fabrication of a pressure vessel, due to some faults in head SF f orming and also carelessness in fit-up, misalignment between the shell and heads exceeds the code tolerance. So, if we want to keep the present circumstance, what remedial actions could be performed i.e. tapper by weld depositing, taper by grinding or...??? Like (2) Comment (16) Follow Reply Privately12 days ago Comments Abhishek Nag, PANTHAK BHALCHAKRA like this 16 comments Jump to most recent comment Martin Koenig Martin Martin Koenig President at Advanced Industrial Solutions Inc.
If there is sufficient material you could grind the misalignment to create a 1 : 3 tapper or if not buildup the area using weld metal to create the tapper, as described in the paragraphs below:
UW-9 DESIGN OF WELDED JOINTS (c) Tapered Transitions. A tapered transition having a length not less than three times the offset between the adjacent surfaces of abutting sections, as shown in Figure UW-9, shall be provided at joints between sections sections that differ differ in thickness by more more than one‐fourth one‐fourth of the thickness of the the
thinner section, or by more than 1/8 in. (3 mm), whichever is less. The transition may be formed by any process that will provide a uniform taper. When the transition is formed by removing material from the thicker section, the minimum thickness of that section, after the material is removed, shall not be less than that required by UG-23(c). When the transition is formed by adding additional weld metal beyond what would otherwise be the edge of the weld, such additional weld metal buildup shall be subject to the requirements of UW-42.
UW-13 ATTACHMENT DETAILS (3) A tapered transition having a length not less than three times the offset between the adjacent surfaces of abutting sections as shown in Figure UW-13.1 sketches (j) and (k) shall be provided at joints between formed heads and shells that differ in thickness by more than onefourth the thickness of the thinner section or by more than 1/8 in. (3 mm), whichever is less. When a taper is required on any formed head thicker than the shell and intended for butt welded attachment [Figure UW-13.1 sketches (l) and (m)], the skirt shall be long enough so that the required length of taper does not extend beyond the tangent line. When the transition is formed by removing material from the thicker section, the minimum thickness of that section, after the material is removed, shall not be less than that required by UG-23(c). When the transition is formed by adding additional weld metal beyond what would otherwise be the edge of the weld, such additional weld metal buildup shall be subject to the requirements of UW-42. The centerline misalignment between shell and head shall be no greater than one‐half the difference between the actual shell and head thickness, as i l
lustrated in Figure UW-13.1 sketches (j), (k), (l), and (m).
UW-42 SURFACE WELD METAL BUILDUP (a) Construction in which deposits of weld metal are applied to the surface of base metal for the purpose of restoring the thickness of the base metal for strength consideration; or modifying the configuration of weld joints in order to provide the tapered transition requirements of UW-9(c) and UW-33(b) shall be performed in accordance with the rules in (b) and (c). (b) Procedure Qualification. A butt welding procedure qualification in accordance with provisions of Section IX shall be performed for the thickness of weld metal deposited, prior to production welding. (c) Examination Requirements (1) All weld metal buildup shall be examined over the full surface of the deposit by either magnetic particle examination to the requirements of Mandatory Appendix 6, or by liquid penetrant examination to the requirements of Mandatory Appendix 8. (2) When such surface weld metal buildup is used in welded joints which require full or spot radiographic examination, the weld metal buildup shall be included in the examination. Like (7) Reply privately Flag as inappropriate 10 days ago Murray P., Vance S. and 5 others like this pg subra pg pg subra QC Manager at HIDADA
P.G.Subra(Hidada Contracting Company)
Weld both sides of the offset to get 1 in 4 tapper.Try to use small diameter electrodes to minimise excess heat input.Grind the joint smoothly to avoid stress raisers.Ensure minimum thickness. Check hardness of the weld & heat affected zone.Complete RT & MT. Like (3) Reply privately Flag as inappropriate 9 days ago Shankaran I., Kevin S . and 1 other like this
robert robert price Authorized Inspector Supervisor at TUV Rheinland of North America
Fewlolow Kevin, The very first thing you need to do is generate a NCR and present it to the AI for review and concurrence of the method of repair on the non-conforming condition. Regards,. Like (3) Reply privately Flag as inappropriate 9 days ago James S., Kevin S. and 1 other like this Zeshan Wasi Zeshan Zeshan Wasi Senior Mechanical Engineer at United Energy Pakistan (Ex BP-Pakistan)
As robert pointed out....the better way to raise the NCR & discuss with AI the situtation. AI is the right person to suggest the better way out to handle it provided that the vessel is coded. Like (2) Reply privately Flag as inappropriate 6 days ago William F ., Kevin S. like this Thomas Spencer Thomas Thomas Spencer Vice President, Sales at RAS Process Equipment
Fix it, then fire EVERYBODY!!! One of the first things that happens during the "in process"
inspection of any vessel let alone an ASME vessel is a "fit up" inspection. Sometimes at the discretion of the AI it is waived. But only because the "back chip" inspection, in most c ases, can confirm a sound fit up of any joint. If you have people in your shop that would weld a misaligned vessel, there must be terrible management to permit such a thing. A long talk with your QC manager would be in order. Like (10) Reply privately Flag as inappropriate 5 days ago Kaveh S., robert P. and 8 others like this Bob McReynolds, P.E. Metallurgical Bob Bob McReynolds, P.E. Metallurgical Manager of Welding & Metallurgical Engineering at CH2MHill / Emirates Nuclear Energy Corporation (ENEC)
Of course process the NCR. Engineering should take a look at API 579 , which is also ASME FFS1(Fitness for service) for analysis methods to evaluate the offset. Like Reply privately Flag as inappropriate 5 days ago
robert robert price Authorized Inspector Supervisor at TUV Rheinland of North America
Kevin, Fellow Spences is correct, this type of condition should never happen. The fitter or welder should have notified the QCM or QC Inspector prior to welding. When the AI or AIS waives a F/U it is based on confidence of the fitter, welder, and QC ensuring the object complies with CODE requirements. As an X-Fitter/welder, I have talked to fittters, welders, and QC of how to inspect the F/U's and what can happen if not F/U propertly. We all must learn something new every day, so take this as an opportiunity and talk with the fitters, welders and your QC personnel. Like (1) Reply privately Flag as inappropriate 4 days ago HUYNH TRAN ANH THU likes this William Fabrizio, PE William
William Fabrizio, PE Pressure Vessel Engineer at Ebara International Corp
Ask the AI how to proceed.
I disagree with Mr. Spencer as firing everyone every time there is an issue is not the way to run a business and you'll burn through local talent in no time - plus the teachable moment is lost to avoid the same mistake in the future. Also, to Mr. McReynolds' point, trying to use API 579 on new construction that is not even U stamped yet is not a way out because the AI should never allow it. It is meant to be an in-service standard, not for new construction. I do not believe that there is some way to harness U-2(g) in order to use API-579 because you are trying to bypass a stated VIII-1 requirement.
As for the other input, there are several unstated assumptions present. I would argue that there may not be enough information given by the OP to fully weigh in because contraindications may be present that have not been mentioned. The biggest assumption (al though not too much of a stretch) is that it is an ASME VIII-1 welded vessel (as opposed to forged or Div 2 or 3). There may also be material requirements that would preclude throwing around a lot of extra weld, like if the parent materials are normalized or the construction is dependent on impacts - extra heat input from extra weld could compromise needed properties.
Finally, at the end of the day, a polished turd is still a turd. Depending on how bad it is, no amount of rework will probably cover the attempt to fix a screwup when a misalignment is involved - and it might come out looking worse than if it was just left alone. Remember that your company's nameplate is being affixed to this vessel. Is this the legacy you want to leave? Will the product instill confidence in your customer, ensuring future work? Removing the head and replacing it correctly is not out of the question. Like (2) Reply privately Flag as inappropriate 4 days ago Thomas E., Christopher W. like this Thomas Easton Thomas Thomas Easton Director of Technical Services at eImaging ltd
Do NOT ask the AI how to fix any mistake YOU have made.
Initiate a NCR and ask your engineering department to offer resolution, then ask your AI if he will accept that decision!
Dependant on the misalignment.....is the head over or under the required diameter?? Can it be removed without damaging the adjacent shell course? Does heat treatment play a part in the final outcome? Is reForming an option? There are many other questions.....? If time permits, bite the bullet and buy a new head, but send your inspector to check the diameter, straight flange and thickness before acceptance. I would suggest using another head supplier, if the previous one apparently caused this in the first place! Like (1) Reply privately Flag as inappropriate 3 days ago Jacobus Johannes G. likes this Thomas Spencer Thomas Thomas Spencer Vice President, Sales at RAS Process Equipment
Hey Fabrizio, loosen your tie a little bit. "Firing Everybody" was a response to indicate the serious nature of an almost unheard of mistake in the fabrication business. It was not meant to be taken literally, that is why nine other people who "got it" liked the comment. My God. (Sorry Gary). As for the local talent? If you employ people who do things like this. Trust me, "talent" local or otherwise isn't a factor. And not to put so fine a point on it, it is exactly how you should run a business. A lost teachable moment? Unless your running a welding school, save it for your three year old or pet dog. Like (2) Reply privately Flag as inappropriate 3 days ago Kaveh S., Vance S. like this
Michael Michael Danko Chief Engineer and Owner at Danko Engineering LLC
Besides, you can't fire EVERYBODY! Some of the people involved may have been union employees, management favorites, legacy employees, or sons/daughters of managers. Those people can't be fired. So by the time the situation is properly analyzed the only people who get fired consist of a BS degree engineer who happened to walk by, Carl the fork truck driver, and Willie the mail boy.
Like (1) Reply privately Flag as inappropriate 3 days ago Kaveh S. likes this Thomas Spencer Thomas Thomas Spencer Vice President, Sales at RAS Process Equipment
Hey Mike! You and Fabrizio should have lunch. Nobody gets fired, but if it happened at our company and you visited us? You would notice many without asses. Why? Because they would have been chewed off. It's only matters if you "get it". Like Reply privately Flag as inappropriate 2 days ago
Michael Michael Danko Chief Engineer and Owner at Danko Engineering LLC
Sure. Most of the time the people directly involved with a major screw-up just get chewed out. Usually if someone gets fired, the bosses have been looking for reasons to fire that person anyway and once in awhile just walking by a major screw-up can be enough to end a career. Like Reply privately Flag as inappropriate 2 days ago
SANJAY KUMAR SANJAY KUMAR PANDEY AGM &Project Quality Lead for DB / Visa PROJECT at L&T Power Baroda
If thickness of both parts is more than min design thk & 1: 3 taper grinding can be done whereever offset observed .When this is not feasible welding by GTAW with approved procedure & qualified welder shall start approx 4" from both end of offset portion , by doing this offset will get reduced (if required 2 layer of argon welding can be done ) .After completion of entire welding same portion shall be checked by RT/UT to check any defect is not found in that area. Like (2) Reply privately Flag as inappropriate 1 day ago Jatin Prabhu, yogesh M. like this
TARUN TARUN BEHL Sr Qa/Qc Engineer at M/s Multitex Filteration Engineers Limites
Hi, if misalignment exceed the code tolerances u will do 1:3 taper either from i nside or outside and get approval from design deptt and issue dcr and show to AI. That is the best method to resolve.... Like (2) Reply privately Flag as inappropriate 1 day ago HUYNH TRAN ANH THU, yogesh M. like this Yashwant Naik Yashwant Yashwant Naik Pressure Vessel Design Engineer at Zamil Industry [PED]
It is better to check minimum thickness requirement as per applicable code first. If thickness requirement is meeting code, then provide weld built up with 1:3 Taper. Core thickness plays very vital role as far stress distribution is concern. After design is finalized then get approval from QC/ AI and proposed new configuration of weld joint to customer for his approval and to check from process point of view. ( As diameter increase or decrease may change in process parameters.
