Why do we need to do purging during p22 and p91 material. Base metal grouping for welding procedure and performance qualification 1. These approved welding procedures may also be found at the following web address. Welding grade 91 alloy steel this information is provided by sperko engineering based on information currently possessed by sperko engineering. The mechanical properties of p11 alloy steel tubes are of great significance to ensure the safe operation of chemical plants, especially to the stability of high temperature and high pressure pipelines in petrochemical enterprises.
Dear sir, 1 what are the points to be taken care during welding of p9 to p91 material 2 if i already did welding of p9 to p9 material and during pmi if one of the material found to be p91 then what thing we have to do to pass that line. Influence of heat treatment in residual stresses generated in. A335 p11 welding procedure chrome moly pipe weldingnews. Challenging weld repair of grade 91 tubing by avoiding pwht. New power plants are in high demand and several hundred can be expected to be built over the next decade. Normally, preheating, interpass temperatures, as well as the postweld heat treatments are really critical for p91 grade material. I would however, caution that you need to ensure the welder understands the requirements of welding p15e materials and that there is a qualified procedure acceptable to product and service conditions. If you are talking for welding p91 to ss, the designations.
This situation has increased the interest in issues related to the processing and fabrication of alloys such as 9cr1mov p91 steels. I have never welded this chromium nickel alloy, only carbon steel and stainless. Achieving sound welds with p91 pipe requires operator skill. The base metal shall conform to the specifications of steel groups 1, 2, 3 as per table 11. Jun 09, 2016 however, p91 is a highercost material that presents some challenges in fabrication. P91 is a very tricky material due to the retained martensite structure and there is a special requirement of post heating. There are further relaxations to pwht requirements under the nbic regarding repair welding of these materials. P91special alloy steel for high temperature application. Therefore, the design of the matching weld metal was based on the tp92 base material composition and reference to the current international specifications for tp91 welding consumables. Effects of post weld heat treatment pwht temperature on. Hello all, i have inspected inspected p91 piping onoff for the alst 5 years.
There is a welding between p91 pipes, when we offered root weld by gtaw with filler wire er 90sb9, the customer who is leading power plant manufacturer wants only er 90sb3 instead of b9. Properties and welding procedure for grade 91 alloy steel 769 conditions, the welding was done. Investigation of weld repair without postweld heat. Welding chromiummolybdenum steel pipe for power plants. There is buttering layer 5mm at the p91 side with p22 welding consumable and after buttering carbon steel consumables are used at root and remained sections. Welding and pwht of t22, t91 and p22, p91 boiler and. Welding a335 p91 generally requires preheating the joint, maintaining interpass temperatures, hydrogen bakes, and postweld heat treatment pwht. Properties and welding procedure for grade 91 alloy steel. Conclusion grade 91 alloy steel is a complex material to work upon. P91 to p91 this procedure employed dual process welding involving a root layer and three hot runs deposited using the manual tungsteninert gas tig welding process, followed by filling and capping. The purpose of this paper is to present the usa view on the question of whether and to what extend weldawelding research supplement. A335 p91 steel is a medium alloy heatresistantsteel produced in accordance with the united states asme standard, part of 9cr1mov steel, an improved 9cr1mo steel, which is essentially based on the original p9 steel with enhanced elements v, nb, n and so on to form a kind of new steel.
Investigation of weld repair without postweld heat treatment. Use of lanl welding procedures and welder qualifications for nonlanl work shall be at the sole risk and responsibility of the subcontractor, and the subcontractor shall indemnify and save l anl and the government harmless from any and all claims, demands, actions or causes of action, and for any. However, p91 is a highercost material that presents some challenges in fabrication. Asme weld number tables are discussed in relation to base metals, filler metals and their positioning in the number tables. The welding procedure approval record wpar is a record of this weld. Chromiummolybdenum steel pipe p91 is a major construction material in these plants and there are particular methods for welding it properly to insure it will hold up. As far as a welding procedure specification wps, you will need to qualify a procedure and this will be based on information obtained from your internet search. The welding techniques and associated equipment come in precautionary. The mechanical properties of p11 alloy steel tubes are of great significance to ensure the safe operation of chemical plants.
Base metal grouping for welding procedure and performance. Preheating, maintaining interpass temperatures, and postweld heat treatment procedures are very critical for p91 grade. When welding p91, preheating, maintaining interpass temperatures and postweld treatment procedures are essential to maintain the p91 grade. Welding consumables a variety of welding consumables with aws or other national specifications are available for p91 materials. Martensite formation in 9 cr1 mo steel weld metal and its. Can anyone provide me ppt on p91 material and how to perform welding and what are the special precaution need to be taken, rgds rohit to post to this group, send email to email protected to unsubscribe from this group, send email to email protected get quotation. Therefore, yes, he would be qualified for a335 p91 materials without further qualification. Using modified 9cr1m0 modified consumable in accordance to our existing procedure of joining p91 material. Welding 16mo3 p11 or p22 boiler and pressure vessel. Material grouping for both procedures and welder approval. Csef, p91, welding, wps, wpqr, wqtr, ndt, preheat, pwht. Since t22 tubes are expected to be less than 4 in diameter, pwht is not required. Using shielded metal arc welding smaw and submerged arc welding saw processes, investigations were carried out to evaluate the effect of welding and pwht procedures on the ambient temperature toughness of tp92 weld metals.
Welding of p9 to p91 material cr4 discussion thread. Pdf challenging weld repair of grade 91 tubing by avoiding pwht. For both processes multilayer welded pads were deposited on serviceaged p91 pipe material with 15mm thickness to simulate weld repairs. Welding procedure specificationwps can specify a maximum interpass temperature, which is done to control weld metal micro structural development, and also ensures that the weld is similar to the welds made in the procedure qualification. Sa 2 t91 or sa 335 p91 is such a ferritic alloy steel that meets this condition. Control of cracks in 9cr1mov p91 material material 1. The manufacturer initially drafts a preliminary welding procedure pwps which is used by one of the manufacturers competent welders to prove that it is capable of producing a welded joint to the specified levels of weld quality and mechanical properties. You need to decide on the welding process, filler metal match to one or the other base material, preheat and post weld heat treatment requirements. Overall, the present study showed that the pulsed current gas metal arc welding of medium to high thickness p91 steels using metal cored filler wires could provide higher deposition rate and welding speed, and enhanced weld bead properties in comparison to solid wires. Welding is one process that is widely used during the construction. The p91 steels are high strength alloys that normally transform completely to martensite during air cooling.
This material has been in use for the last two decades successfully in power plant service. Influence of heat treatment in residual stresses generated. European welding standards john dyson 15th march 2004. Setting up a proper purge displaces the air and and allows y. Thus, weldability is not an intrinsic property of a metal. Welding is the key factor which can be used during the construction.
I estimate that if 750c deg is achieved at root of p91 then at least half of the 308l weld will have the same temperature and then adjacent weld and 316l material may reach 600 c deg and slowly decreasing with the distance. Meet the demanding requirements of welding p91 pipe with. P91special alloy steel for high temperature application in. Where an aws classification is shown, specific con. Advanced gmaw processes help in welding p91 modified waveforms cut training time, improve deposition rate. Postweld heat treatment should also not be performed more than a few days welding to avoid cracking. If not done as per the specified guidelines given in the codes, the material properties can be ruined permanently. May 03, 2017 i have never applied this procedure but it seems to me imposible to avoid heating of ss with this practice. Thus, a slight weave technique with high travel speed is specified. The american welding societys d10 committee on piping and tubing have decided to remove pt91.
However, pwht is not required for p1 materials when weld throat thickness is 5 8 in. For welding,a wide, flat bead is considered best suited. Preheat and postweld heat treatment are mandatory and absolutely critical to the service life of the alloy. Sample welding procedure specifications are available on our website. P91 material welding procedure there are particular methods for welding it properly to insure it will hold up. During the welding process, these metals oxidize significantly in the presence of air, this leaves a dirty looking root with crystal looking sugaring or pitted formations on the metal. Pwht is required for p22 pipe welds greater than 4 diameter or than 12 thick. And the minimum soak time for postweld heat treatment is 1 hour per inch, but no less than 2 hours. A335 p91 welding chrome moly pipe weldingnews center. Investigation of weld repair without postweld heat treatment for p91. Welding procedure specification wps welding procedure no.
A335 p11 is an alloy steel code issued by the astm astm. Meet the demanding requirements of welding p91 pipe with advanced wire processes print article. Its critical to control the heat input before, during, and after welding. Welding procedure specification wps may be generated by an authorized person i. Where an aws classification is shown, specific consumables are available from more than one source. Sperko engineering accepts no responsibility for proper application of this information or for any consequential damages associated with application of. A variety of welding consumables with aws or other national specifications are available for p91. The upper limits of the pwht temperature for the respective weld metals are considered. Basic characteristics and application of a335 p91 steel. Material and method in the present work, it was used a p91 seamless pipe in the normalized and tempered condition, with 152 mm outside diameter and a wall thickness of 18 mm. T91 p91 steel manufactured to astm a335 p91 or astm a2 t91 is a typical tempered martensite in term of microstructure. We use the p91 matching filler, which is er90sb9 or e9018b9 for welding p91 to p22. This grouping is made to reduce the number of welding procedure and performance qualifications, where this can logically be done.
Pulsed current gas metal arc welding of p91 steels using. Table 4 provides examples of welding consumables, and table 5 lists consumables for welding p91. Other groups may be welded providing welding procedure data sheets are accepted by the canadian welding bureau. Welding procedure specifications is a form that contains details of welding groove, welding method to be employed, electrode andor welding rod type and diameter, current, voltage, welding position, welding run number and similar information prep. Two welding processes were selected for the investigation of weld repair procedures without pwht.
Proposed guidelines for welding procedures to ensure quality welding of creep strength enhanced ferritic csef materials muhammad sarwar, mohd amin bin abd majid and mokhtar che ismail mechanical engineering department, universiti teknologi petronas, bandar seri iskandar, tronoh, perak, malaysia email. It is also called 9 cr 1 mo steel based on its composition. The welding of astm a335 p91 pipes in a power plants main steam pipeline, jiangsu province, china. There are a lot of problems being dealt with regarding improperly welded p91 materials in power plant piping and headers. Failure to follow the procedures will result in catastrophic failures. Require welding procedure if this joint is recommended in p91. To get better control on the thick walled pipes it is important to introduce the. Properties and welding procedure for grade 91 alloy steel 771 4. Compared to its predecessor, the t22 or p22 grade, grade 91 exhibits high strength up to temperatures in the. To unsubscribe from this group and stop receiving emails from it, send an email to material. Welding procedure specification wps asme boiler and pressure vessel code, section ix sheet 1 of 3. They can be welded by many common welding methods including smaw, saw, gsawtigmig, and fcaw, etc.
Sawp9101 consumables base material welding process root. Presently, there are no national specifications for tp92 steel welding consumables in either asmeaws or bs en standards. Introduction highcr ferritic heatresistant steel is a material. Welding has an important effect on the microstructure and failure to follow the procedures will result in catastrophic failures. The most important and difficult task is to maintain its unique microstructure. This problem you are having is likely due to a combination of welding procedure and heat treating procedures.