Re: [MW:0] Uphill Vs Downhill Welding
Bhavesh Patel
Dear Friends
What is the criteria for selecting Uphill/Downhill weld progression in a Pipeline/Piping? Is it mandatory to use uphill progression in a WPS qualified under ASME Sec IX ?
Thanks and Regards
Harikrishnan N S
Punj Lloyd Ltd, Mumbai
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mahendran p
Dear Bhavesh,
Just to clear my doubts. The 405.3 mention it not mandatory, but in 405.4(d) mention need to requalify.
Pls explain.
Thk u.
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sethurama lingam
Dear Mr. Harikrishnan N S,
Welding uphill, or welding from the bottom to the top on vertical welds, provides much more penetration than welding downhill. Therefore, it is required in most instances to weld uphill by the industry.
In down hill welding the penetration and thickness of weld metal deposited in each layer is very less compared to uphill and completion time of joint is less than down hill. Generally down hill used in UG cross country pipe line as per API1104 other than all only used uphill welding including the compressor station, SV station also.
Mostly the client spec/code requirement in pressure vessel and process piping, AG piping used only up hill welding and also the filler or electrode manufacturer specification with respect to ASME sec II C
Regards
Sethu Ramalingam.p
John Henning
Vertical progression is a non-essential variable, QW-405.3, for procedure qualification for general welding with most processes. Therefore, for these WPSs while vertical progression must be addressed it does not require additional procedure qualification tests to change progression.
When impact testing is required by the design/construction code, Vertical welding with uphill progression must be qualified if it is going to be used in production (supplementary essential variable, QW-405.2). This is because vertical – uphill welding tends to have the highest heat input and therefore have the greatest effect on impact properties of the HAZ and weld metal.
QW-405.4 only comes into play when specialized welding procedures for corrosion resistant overlay or hard facing overlay are required.
To those unfamiliar with using ASME Section IX, I give the following advice. The list of variables contained in ASME Section IX, Article IV, Welding Data, do not stand alone. The variables do not directly apply to welding in general and should not be quoted, imposed, or used independently. In order to come into effect they must be specifically called out either for the process employed (See tables QW-252 through QW-265, QW-290.4) or for performance in QW-350 (see tables QW-352 through QW-357). Article IV can be likened to a dictionary or encyclopedia, it is simply a list of most of the standardized variables employed in Section IX . Without specific selection, individually they have no application or meaning just as random word in a dictionary or random article in an encyclopedia would likely be of use when you are searching for specific word or specific information.
Note that some special situations may have a separate list of requirements or essential variables, as with, for example, QW-288 tube-to-tubesheet qualification by mock-up welding {applicable only if required by the design/fabrication Code}. Or, as another example, if you using “buttering” or weld build up to avoid PWHT of the final joint you will have to meet the requirements of QW-283 in addition to the applicable process requirements in QW-350.
I hope this clarifies this issue for you. Please let me know if you have further questions.
John
george....@gr.bureauveritas.com
Only the welder's qualification is affected by the change of progression
Dr. G. Dilintas - Authorized Inspector Supervisor
I&F Regional Technical Manager
Bureau Veritas Piraeus - Greece
Tel: +30 210 40 63 113/4
Fax: +30 210 40 63 118
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Harikr...@punjlloyd.com
Sent by: material...@googlegroups.com 08/07/2010 08:21
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