The current status of BS 287-1 and ISO 9606-1 are explained in What is the current status of EN 287-1 and BS EN ISO 9606-1 for welder qualification? Due to this complex situation, it is possible that fabricators will be moving from EN 287 Part 1 to ISO 9606 Part 1, or using the two in parallel, depending on the type of product being manufactured. This means it is necessary to fully understand each standard and the variations between the two. This Job article will provide some insight into the differences between the standards.
There are some differences between the two specifications with respect to the essential variables and their ranges of approval. An essential variable is a welding parameter or characteristic that, if changed outside its range of approval, requires the welder to be re-qualified. Since a welder qualification test is a test of the welder’s skill the essential variables and the ranges of approval of a welder qualification test are not necessarily the same as those of a welding procedure qualification test. The relevant essential variables are listed in Table 1 for both specifications. The differences between the two are highlighted in yellow.
As EN 287 Part 1 may still be used, a welder qualification may be carried out to EN 287-1 and will remain valid as per that standard, until such time as the standard is withdrawn and the validity lapses. At that point, welders qualified in accordance with EN 287 Part 1 must be retested in accordance with ISO 9606 Part 1 OR a welder qualification certificate compliant with ISO 9606 Part 1 must be issued by the examining body. The Introduction to ISO 9606 Part 1 states that “…. at the end of its period of validity, existing qualification tests of welders in accordance with …..a national standard may be revalidated according to this International Standard…..providing that the technical intent ……is satisfied….”. The test methods and acceptance standards are identical so it should be possible for the examining body to issue a new certificate taking account of any changes in the ranges of approval between the two specifications. With the existence of two welder qualifications, it is worth looking at the differences between the two.
The differences between EN 287 Part 1 and ISO 9606 Part 1 are that:-
- The parent metal is no longer an essential variable. The parent materials in EN 287 Pt1 are grouped as in PD CEN ISO/TR 15608, the same as the requirement for welding procedure qualification in ISO 15614 Pt 1. The requirements in ISO 9606 Pt 1 are now similar to those in ASME IX in that, for example, a welder may be qualified to weld stainless steel by using a stainless consumable on a carbon steel test piece. The philosophy behind this approach is that what we are testing here is the welder’s ability to use the relevant consumable: the effect of welding on the parent metal is addressed during procedure qualification. The only departure from this is for autogenous welds where the range of approval is that of the parent metal group.
- The filler metal composition has become an essential variable. Similar compositions are grouped together as FM1, non-alloy and fine-grained steels; FM2, high strength steels etc. In addition to the groups covering the steel compositions, there is a group FM6, nickel and nickel alloys. Note that ISO9606 Pt1 is to qualify welders for the welding of steels so this group does NOT qualify the welder to weld nickel-based alloys but is intended for applications such as dissimilar metal joints between low alloy and austenitic stainless steels. It can also be used to approve a welder to use a high nickel alloy consumable on 9% nickel steels.
- The range of approval on thickness for butt welds is now based on the deposited weld metal thickness. The parent metal thickness is still the essential variables for fillet welds.
- In MIG/MAG welding ISO 9606 Pt1 has made metal transfer mode an essential variable – dip transfer qualifies for globular and sprays transfer but not vice versa.
- The requirements with respect to validation of the welder qualification certificate are the same, but those for prolongation (described as ‘revalidation’ in ISO 9606-1) are different. The validity of the welder certificate must be confirmed at six-monthly periods by the manufacturer according to both standards. According to ISO 9606-1 (Clause 9.3), the following methods are permitted for revalidation:
a) Retesting the welder at three-yearly intervals
b) Every two years, provided that: two test welds have been made and tested by radiographic or ultrasonic testing or destructive testing within the previous 6 months and records are kept.
c) Unlimited provided that the welder is working for the same manufacturer, the manufacturer’s quality system has been verified in accordance with ISO 3834-2 or ISO 3834-3 and the manufacturer has documented that the welder has produced welds of acceptable quality made in accordance with an application standard.
- Method (c) above is not included in EN 287-1. Attention is drawn to the fact that this will not be permitted for equipment under the Pressure Equipment Directive (PED), The test programme specified by EN 287 Pt 1 is essentially unchanged in ISO 9606 Pt 1 although there are some additional requirements. The test methods now reference ISO specifications for visual examination, radiography, bend testing, fracture testing, macro-examination, and ultrasonic testing. In a multi-process test piece the situation regarding stop/start positions has been clarified – there must be at least one stop and restart for each process: where macro-sections are substituted for the fracture test of a fillet weld test piece one of the macro-sections must include a stop/start position. To prove that this has been carried out it will, therefore, be necessary for the test house to record the presence of the stop/start.
|Essential Variable||EN 287 Pt1||EN ISO 9606 Pt1||Comments|
|clause no||clause no|
|welding process||yes||cl 5.2||yes||cl 5.2|
|material group||within ISO/TR 15608 Group||Table 2||no||the material group is not an essential variable in ISO 9606-1|
|product type (plate/pipe)||plate qualifies pipe >150mm in PA PB PC||cl 5.3||plate qualifies pipe >75mm in PA PB PC PD||cl 5.3||pipe≥25mm OD qualifies plate in both standards|
|pipe outside diameter||yes||Table 6||yes||Table 7|
|material thickness||butt – yes||Table 5||no||cl 5.7 and Table 6||In ISO 9606-1 the qualified thickness of a butt weld is the deposit thickness|
|fillet – yes||Table 7||yes||Table 8|
|joint type (butt/fillet)||butt does not qualify fillet||cl 5.4||butt does not qualify fillet||cl 5.4||fillet weld test supplementing butt test is permitted in both specs|
|material backing – deletion||yes||Table 9||yes||Table 11|
|filler material group||no||yes||cl 5.5||ISO 9606-1 includes 6 separate filler metal groups – see Table 2 and Table 3|
|filler/autogenous||deletion or addition of filler metal – yes||cl 5.2||addition of filler metal – yes||cl 5.6||In ISO 9606-1 filler additions qualify for autogenous but not vice versa|
|filler material type (electrode/wire)||solid qualifies cored and vice versa: process 135:138||Table 4||solid qualifies cored and vice versa: process 121, 125 . 135, 138||cl 5.2||ISO 9606-1 has added submerged arc welding to the qualified processes|
|filler material coating/core||yes||Table 3||yes||Table 4||both specs cover coated electrodes and cored wire|
|Table 4||Table 5|
|weld deposit thickness||butt – yes||Table 5||butt – yes||Table 6||the parent metal thickness is the essential variable for fillet welds|
|fillet – no||fillet – no|
|welding position||yes||cl 5.8 Table 8||yes||cl 5.8 Table 9 Table 10||ISO 9606-1 has separated butt and fillet weld positions into two tables|
|metal transfer mode||no||yes||cl 5.2||In ISO 9606-1 dip transfer qualifies spray but not vice versa – process 131, 135, 138|
|single/multi layer||yes – fillet welds only||Table 10||yes – fillet welds only||Table 12||multi-layer qualifies single but not vice versa|
|acceptance standard||ISO 5817||cl 7||ISO 5817||cl 7|
|QL B/C||QL B/C|
|validity||confirmed at 6 month intervals||cl 9.2||confirmed at 6 month intervals||cl 9.2|
|prolongation||every 2 years by examining body||cl 9.3||retest every 3 years OR revalidate every 2 years OR unlimited, provided certain requirements are met||cl 9.3||Method of revalidation must be stated on the certificate at time of the initial test|