Rabu, 06 Februari 2008


sources : Eng Tips

There are many discussions regarding procedure qualification on this fine Forum,which I have studied over and over but I still have some confusion on my situation.Our shop has been mainly devoted to Mil spec welding requirements (mostly Navy). There has been a growing trend in the engineering drawings that are coming in to apply the AWS (D1.1, D1.6) requirments. Can I use our qualified and fully matured Mil and NAVSEA welding procedures as "prequalified" procedure and write up an AWS procedure (providing of course that all materials, essential/non-essential variables are identical) and go into production w/o qualifying the AWS procedure or retesting welders? As I see it, the Mil spec and the AWS procedures will be clones.All clarifications on what I must do are welcomed.Thankyou in advance.
SJones (Petroleum)
3 Feb 07 0:46

There is nothing stopping you doing what you propose. All you have to do is ensure that all the variables, test standards, and acceptance criteria meet or exceed the D1.1 requirements.
Steve JonesMaterials & Corrosion Engineer

metengr (Materials)
3 Feb 07 10:31

AWS B2.1 -2005 "Specification for Welding Procedure and Performance Qualification" specifically allows what you describe above under 2.1.3 Procedure Qualification.

gtaw (Structural)
4 Feb 07 22:44

AWS D1.1 and D1.6 have provisions for prequalified WPSs. You can write the WPSs without the need to have them supported by PQRs.You will have to compare the welding variables and essential variables of your existing military WPSs against the requirements of AWS. You may encounter some problems with the details of the weld grooves you use. Again, you will have to compare the details of the grooves to those of the prequalified groove details of D1.1 and D1.6. You will also run into problems with the filler metals. You may be listing military filler metals on the existing military WPSs. You will have to specify the filler metals using AWS specification numbers and classification numbers. If you are using SMAW, you will have to replace the A group numbers with AWS F numbers.It may be much easier to simply develop new prequalified WPSs rather than do a detailed revision of the existing WPSs and catching each and every detail.
Best regards - Al

tc7 (Mechanical)
5 Feb 07 8:57

Thanks all for your advice.GTAW- the Navy and other Mil specs do already call out selections of AWS A5.10 fillers, so I think I'm in good shape there.Great! Thanks again for your responses.Regards,tc

Minggu, 03 Februari 2008

Tanya jawab WPS


How do I become a certified welder?
You need to take a test. This test is a practical exam that explores your ability to make sound welds. For most codes there is no written test or training requirements.

Can I do the welding at my facility and send the test assembly to you for evaluation?
Yes, most Codes do allow this.

Which test do I take?
This is the big question. It all depends on what type of work you are doing and which code you are working to. Each code has its own test that, if passed, will qualify you to do work to that code and only that code.

Can you give me some examples of the various tests?
Yes, they are as follows:
A. If you are welding structural steel like a car trailer, a machine support or a handrail, then
probably AWS D1.1 is the right thing to do. If you test and pass on a 3/8" thick plate, using a
single vee groove with backing, in the vertical position, you’ll be qualified to weld in the flat,
horizontal and vertical positions on 1/8" to 3/4" thick steel members.
B. If you are welding pipe that is being used to contain a fluid or gas, such as a high temperature
water line, then ASME Section IX is probably the way to go. If you test and pass on a 5"
Schedule 80 (3/8" thick wall) steel pipe in the 6G (45 degree incline position), you will be
qualified to weld 2.875" OD pipe, 3/4" wall thickness and less, in all positions.

Is a welder who has passed an ASME Section IX qualification automatically qualified for AWS D1.1?
No, each Code only qualifies for itself. There is no hierarchy. However, sometimes the owner can be persuaded that one Code is as good or better than the other.

Are all welds created equal?
No, there is no such thing as the perfect weld. All welds contain discontinuities. Each Code determines the extent of the discontinuity before it is classified a defect and must be repaired. For example, B31 .1 does not allow any lack of penetration. While B31 .9 only requires that the lack of penetration does not exceed more than 1.5" in any 6" length of weld and that the incomplete root penetration does not exceed the lesser of 1/32" or 20% of the required thickness.

If the work is being done to B31.1 and the temperature is 300 F at 500 psig,do we have to RT?
No, these conditions require VT only. (See table 136.4 of B31 .1) or read the above Code section, to determine when RT/UT is required.

What do I do if work is being done to B31. 1, and the service conditions only require VT, and the owner requests, outside of the contract, that RT be performed?
Inform him that for the service conditions the Code specifies that only VT be performed. This is due to the fact that the Code has a large enough safety factor built into the design that even if there were discontinuities contained inside the weld, that VT could not detect, that it would still give acceptable service life.

How good do the welds have to be if the contract states that conformance to B31. 1 is required and the service conditions would require only VT by Code, but the contract has a provision that the owner may perform random RT?
A. If the specifications do not specify what the acceptance criteria is to be, then you could make the argument that the acceptance criteria is the same for RT as it is for VT. That is, only root and face conditions will be considered and that any discontinuities contained within the weld will be ignored. This scenario does not raise the cost of producing the welds. It only increases the cost of inspection.
B. If the specifications state the acceptance criteria, then that quality of weld must be present on all welds. This scenario could radically increase the cost of producing the welds.

Do we have to produce a weld map to meet the requirements of B31?
No, The B31 Codes only require that examination be performed on 100% of the welds. A weld map certainly helps to verify that you have performed this function but it is not required.

Is there a difference between examination and inspection?
Yes, B31 .1 states that there is a difference between the two. Inspection performs a Quality Assurance function while examination performs a Quality Control function. That is, the examiner is the one who physically performs the NDE and records the results. An inspector has the right to audit any examination, to inspect the piping using any appropriate examination method required by the engineering design of the Code, and to review all certifications and records. The intent of B3.1 is to have the contractor perform the examination and the owner perform inspection

Do we have to hire an outside testing agency to meet the VT requirements for B31. 1?
No, Paragraph 136.3.1 states that examination denotes the function performed by the manufacturer, fabricator, erector or a party authorized by the owner. Paragraph 136.3.2 states the requirements for that examiner. The examiner can be qualified to SNT-TC-1A, CP-189, AWS QC-1 or may be someone that has been qualified in accordance with a program that is based on the following requirements-
a. instruction in the fundaments of the NDE method;
b. on-the-job training;
c. an eye examination performed at least once each year;
d. pass an oral or written examination
e. shall have performed the NDE method at least once per year.
We have a job where the piping system is clearly within the scope of B3 1.9 and outside the scope of B31. 1; however, the contract requires B31. 1. Can we perform the work to B31.9?

Menyiapkan WPS Sebelum Project Berjalan

AWS D.1.1 Struktural WPS (PART 1)

Sebelum sebuah project construction dilakukan maka pihak contractor harus menyiapkan terlebihdahulu WPS sesuai dengan standard yang digunakan.

Pembuatan WPS adalah tanggung jawab dari manufacturer atau contractor seperti yang di sebutkan dalam AWS D.1.1 alinea Maksudnya adalah perusahaan fabrikasi atau yang membuat barang setelah ditunjuk oleh owner (yang punya barang) berkewajiban membuat WPS qualifikasi terlebih dahulu sebelum proses production welding dilakukan sesuai dengan persyarata yang di berikan oleh owner dalam lembaran client specification untuk welding dan performance qualification, atau yang sejenisnya.

Timbul pertanyaan seberapa banyak WPS perlu dibuat untuk suatu project? Untuk menjawab pertanyaan di atas, maka pihak contractor/ manufacturer wajib untuk menganalisa joint joint yang akan dilakukan dalam pembuatan project tersebut. Di bawah ini dibuat langkah langkah untuk membuat WPS yang bisa mengcover semua joint yang ada dalam project tersebut.

1. Pembuatan sebelum Project :
Pembuatan WPS sebelum production welding berjalan. Pembuatan ini berdasarkan shop drawing yang diberikan oleh Owner pada saat tahap Bidding. Pada tahap Bidding tawar menawr harga project, disana dihitung semua biaya dari semua proses produksi dari A-Z.

2. Pembuatan Saat Project berlangsung.
Ada kalanya saat project berlangsung terjadi beberapa masalah dan kendala di luar perhitungan.

Contohnya adalah :

1. Kehabisan consumable merk yang di sepakati sehingga terpaksa di buat WPS baru dengan
merk lain. (Ini berlaku bila owner menjadikan trade mark sebagai essential variable).
2. Proses Welding : Suatu hal yang lumrah kalau terjadi perubahan proses welding yang
tadinya mau pakai proses SMAW lalu diganti dengan SMAW karena dengan FCAW
produktifitas lebih tinggi.

Seberap banyakWPS yang dibutuhkan dalam sebuah project akan tergantung dari range qualification yang dilakukan pada saat running test coupon.