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ASME 9 - Introduction

These articles are intended as a very general guide to ASME 9. They are a collection of my own personal notes which were written to aid my understanding of the code. Their are certain exceptions in the code that are not covered in these articles, therefore you are urged to study the code carefully before using its rules to carry out any welding qualifications. Brief Introduction
Welding qualifications to ASME 9 are for use with the ASME boiler and pressure vessel code or the ASME pipework codes. For use with any other code or standard agreement between all contracting parties should be obtained.

The ASME boiler and pressure vessel code embraces its own QA system which revolves around satisfying the rules of the code.  This demonstrates that an accredited fabricator has some degree of competence permitting them to perform a large amount of their own inspection without the involvement of an Independent Inspection Body, which would be required by other standards for similar inspections. 

This is why welding qualifications carried out under the ASME code do not require Independent Inspection, a fabricator can qualify his own procedures and welders using the ASME code rules.  However this may not be acceptable to the European Pressure Equipment Directive which requires all welding qualifications in inspection categories two and above to be approved by a Notified Body.

However there is nothing stopping anybody using any of the rules of the ASME code without being ASME approved, but to prove your  competence in welding an Independent Inspection Body is recommended to approve your welding tests.

The advantage of ASME 9 is that its very workable and very comprehensive, if you have a question you will almost certainly find an answer somewhere in the code, which is more than can be said for its European equivalent EN288.

The ASME code may at first glance appear complex and very legalistic but once you understand the basic rules they are very easy to apply in practice.  Its main advantage is that it requires very few welding procedures unlike EN288 which requires a ridiculous number if it is applied correctly.

The main advantages of ASME welding procedures are:

  • All joint types approve each other. i.e. A double sided weld approves a single sided weld and vice versa.
  • No limits on diameter approval for pipe. A plate procedures can be used to weld any diameter of pipe
  • Materials and welding consumables are listed in groups
  • Any butt weld will qualify all fillet weld sizes on any parent metal thickness.
  • A welding procedure qualified in one position approves all positions unless impact tests are required then only a vertical up approves all positions.
  • The code covers wide range of welding processes and applications such as hard facing, stud welding, brazing etc.

If you have difficulty in appreciating the above advantages you need to understand the basic philosophy behind welding procedure tests described in the ‘Basic Guide’.

The main advantages of ASME welder approval tests are:

  • There is no minimum parent thickness, only maximums, and they are applied to the deposited thickness of the weld not the parent metal thickness.
  • There is no upper limit on diameter approval, only a lower limit.
  • Any butt weld approval will qualify all fillet weld sizes on any parent metal thickness..

The main problem with the ASME code is that it treats all welding processes separately and imposes separate restrictions for each on both procedures and approvals. It is therefore prudent to check what the code says about the welding process you intend to use before you carry out any welding tests.

The ASME code covers a very wide range of welding processes and applications such as hard facing, stud welding, brazing etc.

Application standards such as the B31 pipework code may impose additional requirements and limitations in some cases. 

The code is divided into 4 parts as follows:

QW100General introduction to testing requirements etc.
QW200Procedure Qualification details.
QW300Performance Qualifications (Welder Approvals) details.
QW400 Welding Data. This is the biggest section of the code and covers data for
both procedure and performance qualifications. It includes:
  • Material and consumable data
  • Test requirements.
  • Approval ranges for thickness, diameter, joint configuration and welding positions
  • Definitions used in the code.

* Artical originally from here and dated 14 August 2004.

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