The project requires Killed Steel treatment on Pipe, Plate MTC.

Fully killed is the term to describe de-oxidized steel. After the steel is made, it is then poured into the continuous caster to make a long slab of steel. Think of a sausage maker – molten steel goes in at the top and rectangular slab comes out the bottom. This is called casting. During casting, small carbon monoxide bubbles can form between the steel grains if the oxygen is not removed. If you’ve ever painted a door and seen bubbles in the paint once you apply it you’ll recognize the similarities. To stop these bubbles appearing you paint slower, but … Continue reading The project requires Killed Steel treatment on Pipe, Plate MTC.

Stainless steel 347H and PWHT

”In the welded condition many stainless steels are susceptible to rapid intergranular corrosion or stress corrosion cracking. This is because the heat from welding sensitizes the base metal heat affected zone (HAZ) and the weld. Sensitization is the condition where chromium carbide precipitation at the grain boundaries (from a heating process, e.g., welding, hot forming, hot bending, service temperature, etc.) reduces the amount of chromium in solution in the stainless steel. The temperature range for sensitization to occur for austenitic stainless steels is approximately 700 °F to 1500 °F. Since the carbides precipitate in the HAZ or weld deposit at … Continue reading Stainless steel 347H and PWHT

Change electrode manufacture, vendor in welding WPS.

If welding is to be performed according to a welding procedure specification, it is possible that changing the electrode manufacturer will invalidate the approval of the procedure to the code/standard on which it was based. The manufacturer or ‘trade name’ of the electrode can be classed as an essential variable in a given weld procedure. The extent to which re-qualification is necessary will vary from code to code. For example, in EN ISO 15614-1[1] and in the UK standard BS 4515:2004[2], approval is only restricted to the specific make of electrode if impact testing is required as part of the procedure qualification. On the … Continue reading Change electrode manufacture, vendor in welding WPS.

Plastic (PPE, HDPE) welding standards

There are tests for plastic welds, below is a selection of relevant tests. EN 12814-1:1999: ‘Testing of welded joints of thermoplastics semi-finished products – Part 1: Bend test’ EN 12814-2:2000: ‘Testing of welded joints of thermoplastics semi-finished products – Part 2: Tensile test’ EN 12814-3:2000: ‘Testing of welded joints of thermoplastics semi-finished products – Part 3: Tensile creep test’ EN 12814-4:2001: ‘Testing of welded joints of thermoplastics semi-finished products – Part 4: Peel test’ EN 12814-5:2000: ‘Testing of welded joints of thermoplastics semi-finished products – Part 5: Macroscopic examination’ EN 12814-6:2000: ‘Testing of welded joints of thermoplastics semi-finished products – … Continue reading Plastic (PPE, HDPE) welding standards

Weld proximity, between two seams standard

Weld proximity is covered by a number of international standards. Extracts from these standards are shown below and summarised in the following table: Standard Applies to Minimum distance between weld toes Notes BS 2633:1987 Ferritic steel pipework 4t t= nominal thickness of the pipe See below for notes on attachment welds. BS 4515:2009 C-Mn pipelines 4t t= pipe thickness BS 2971:1991 Carbon steel pipework Agreed by parties – PD 5500:2012 Pressure vessels 4e or 100mm whichever is greater e= design thickness Refers to the staggering of longitudinal welds ASME B&PV Boilers and pressure vessels Not specified – BS 2633 ‘Class I … Continue reading Weld proximity, between two seams standard

Time delay before applying NDT in welding

The following standards stipulate delay time before inspection: BS EN 1011-2:2001 Welding – Recommendations for welding of metallic materials – Part 2: Arc welding of ferritic steels (with amendment AMD 14926 Feb 2004) Paragraph 18 states: ‘Due to the risk of delayed cracking, a period of at least 16 hours is generally required before the final inspection is made of as-welded fabrications. The minimum time may be reduced for thin materials below 500N/mm2 yield strength or increased for materials of a thickness greater than 50mm or of yield strength over 500 N/mm2 … Welds that have been heat-treated to reduce hydrogen content … Continue reading Time delay before applying NDT in welding