After the welding, the material is kept at elevated temperature to keep it dry before post weld heat treatment pwht. I am working on a asme section ix procedure qualification using a335 grade p91 pipe. P91 to p91 this procedure employed dual process welding involving a root layer and three hot runs deposited using the manual tungsten. Heterogeneous welding must also be qualified according to asme requirements, especially, p91 welding with p22. The mechanical properties of p11 alloy steel tubes are of great significance to ensure the safe operation of chemical plants. The assertion that nbic has no provision for weld repair of grade 91 steel without pwht is not correct. Influence of heat treatment in residual stresses generated.
Nevertheless, this process is now successfully used for welding p11, p22 and p91 creep resisting steels 7,8,9. Postweld heat treatment restores toughness to the weld deposit and the haz. As a result, codes and procedures for p91 applications are stringent. In principle, you cannot use this as chemical compositionano. A335 p5 seamless pipes, a335 p22 seamless pipe, p91 tubes. Similar butt welds were manufactured of p22p22 and p91 p91 as well as dissimilar butt welds of p22 p91. Welding grade 91 alloy steel this information is provided by sperko engineering based on information currently possessed by sperko engineering. This standard was revised to correct the amperes under electrical characteristics and to delete all references to asme s material numbers. Welding chromiummolybdenum steel pipe for power plants. They can be welded by many common welding methods including smaw, saw, gsawtigmig, and fcaw, etc.
A335 p11 welding procedure chrome moly pipe weldingnews. A brief description of the welding parameters and consumables for the affected procedures follows below. 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. Shielded metal arc welding of carbon steel m1p1s1, group 1 or 2, 18 through 34 inch thick, e6010 vertical uphill followed by e7018 vertical uphill, aswelded condition, primarily pipe applications prepared by the american welding society aws b2 committee on welding procedure and performance qualification under the direction of the. The welding input parameters require strict control during welding and appropriate preheat and post weld heat. A335 p91 is formed by normalizing at 1050 c, air cooling down to 200 c. The temperatures and the cooling rates are very important for p91 material. This document established the foundation and framework for standard welding procedure specifications. Jun 09, 2016 the heat of the welding process makes the weld deposit and neighboring haz brittle when welding p91.
Creep crack growth ccg tests were carried out on compact tension ct specimens machined from p91 weld joints prepared using multipass shielded manual metal arc welding procedure. The american welding societys d10 committee on piping and tubing decided to remove pt91 materials from its ex. The welding parameters for each layer were selected in order to maximise the refinement of the haz associated with subsequent welding layers, by using the twolayer refinement criterion suggested by alberry. Chromiummolybdenum steel grade p91 is a major construction material in these plants and there are particular methods for welding it properly to insure. P91 is a very tricky material due to the retained martensite structure and there is a special requirement of post heating as well as spcial ht cycle. The qualifications of welding procedures and welders obligatorily be done according to the welding procedure specification. Sawp9101 consumables base material welding process root. Investigation of weld repair without postweld heat treatment. Gastungsten arc welding of aluminum mp22 to mp22, 18. Thus, a slight weave technique with high travel speed is specified. The main focus was to examine the mechanical properties of weld joins. No welding to be permitted without a wps qualified by third party or notified body.
Normally, preheating, interpass temperatures, as well as the postweld heat treatments are really critical for p91 grade material. The post weld heat treatment was conducted at 750c for holding times 0. Similar welds of p91 steel were subjected to isothermal heat exposure at 650 c for 650, 2007, 5000 and 10 000 hrs. A wide variety of welding p91 material options are available to you, such as equal. I am planning to use this procedure qualification pqr as the basis for a welding procedure specification wps for a seal welding a182 grade f91 valve body forging to valve bonnet forging. New power plants are in high demand and several hundred can be expected to be built over the next decade. Effect of post weld heat treatment and filler metals on. 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. Iso certified supplier of high quality astm a335asme sa 335 p5, p9, p11, p22, p91 seamless pipes. Dissimilar ferrous metal welding using advanced gas metal arc welding processes 127 table 2.
Specimens with two notch locations have been employed, i within the weld metal, between the centreline and the fusion line and ii in the heat affected zone. Metalspiping not only provides premiumquality t91 p91 seamless pipes and tubes but also supplies optimum filler metals. Presented paper regards devoted to checking the properties of weld joints of steel p91 considering heat affected zone. The use of a rutile flux system does impose certain limitations on the achievable weld metal properties, toughness in particular. Experimental procedure the base material was taken from a seamless pipe of astm a335 p91 steel provided by dalmine tenaris italy. Astm a335 p9 tube pwht with tig sg crmovnb 91 welding rodseatment. Welding method 6 currently allows for you to weld tube to tube connections internal to the boiler or hrsg setting without pwht for p15e materials using approved nibase alloys. I have never welded this chromium nickel alloy, only carbon steel and stainless. Alloy steel seamless pipestubes astm a335 p5, p9, p11, p22, p91. Can you mail me wps for astm 335 p91 to astm 335 p91 material,thickness 10 mm to 32 mm. Pwht was 750 degrees of celsius for 3 hours cooled in air followed by 700 degrees of celsius for 2 hours cooled air, again. 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. Welding consumables for p92 and t23 creep resisting steels. T91 p91 steel manufactured to astm a335 p91 or astm a2 t91 is a typical tempered martensite in term of microstructure. The qualification of welding procedures must be complied with the requirements of asme section ix and the applicable design code. For welding,a wide, flat bead is considered best suited. 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. Properties and welding procedure for grade 91 alloy steel. Combination lowalloyed steel to mild steel dissimilar lowalloy steel stainless steelcarbon or lowalloy steelssteel stainless steel stainless steel observations welding parameters shall be. In this case, welding method tig in argon for the root pass and mma for filler and cap passes.
Properties and welding procedure for grade 91 alloy steel 769 conditions, the welding was done. Preheat and postweld heat treatment are mandatory and absolutely critical to the service life of the alloy. Specification for welding procedure and performance qualification. Microstructural study of welded joints in a high temperature. Creep crack growth behavior of a p91 steel weld sciencedirect. No definite standpoint on how long a weld can be left in the as welded condition. Possible combinations of ferrous metal grades 1214. Fumes material saety data sheets msds are availale on our wesite. While csef alloys such as p91 are designed to maintain strength as the environmental temperature rises, one of the biggest challenges in welding p91 is the material s sensitivity to heat changes during the welding process. For both processes multilayer welded pads were deposited on serviceaged p91 pipe material with 15mm thickness to simulate weld repairs. Jul 07, 2002 at the moment we are welding 6 tubes, 7.
Base material asmeaws specifications are approved for using p91 base material and weld metal. May 03, 2017 i have never applied this procedure but it seems to me imposible to avoid heating of ss with this practice. Stress corrosion cracking risk of 9%cr martensitic steels between welding and pwht s huysmans, laborelec electrabel gdf suez, belgium main points. Table 3 illustrates base metal code cases that have been issued for asme section i construction.
To get better control on the thick walled pipes it is important to introduce the. Because precision and stability in temperature control are extremely important when welding p91 pipe, induction heating is a solution that offers better control and. A335 p11 is an alloy steel code issued by the astm astm. Sperko engineering accepts no responsibility for proper application of this information or for any consequential damages associated with application of this information. Welding is the key factor which can be used during the construction. The welding techniques and associated equipment come in precautionary phase. Saw p91 01 consumables base material welding process root.
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