The grand opera in treatment of stainless steel canal is cold hot punch

The grand opera in treatment of stainless steel canal is cold hot punch

Stainless steel pipe fitting, especially 3, bend and size first class are used in plumbing construction process more and more general, because its have take shape,this basically is capability of good, compression is strong, solder the form is simple wait for a characteristic, with assuring conduit bear control capacity, be in especially in craft plumbing so petro-chemical in waiting for high temperature high pressure and path of combustible easy cartridge igniter, of pipe fitting reasonable the action that makes the stand or fall of in order to and quality of pipe fitting itself is rising to hold the balance directly.
　　
because such, it is especially in process of conduit design, installation in high pressure of petro-chemical industry high temperature and project of path of combustible easy cartridge igniter, no matter from the design type selecting or treatment are made, till construction installation and each examining link, the design is made and installation unit staff should guard a pass strictly, assure its type selecting, with material, make, installation and examining quality, reach the meeting in producing a course to cause the loss that difficult Si estimates in plant construction otherwise.
From inside construction process, the quality that we discover to pipe fitting arrives basically puts in the problem of the following respects:
　　
One, the wall of pipe fitting is large not all
Pipe fitting wall is large basically all do not happen in pipe fitting to be out of shape the largest position. The mural thickness that is like bend back at other position; The wall of nozzle and pipe fitting body is large differ. Set in national relevant specification. The wall of pipe fitting is large the 1 2 that decreases small amount to must not exceed its name ply greatly most, 5, but discover in spot actual measurement, some walls are large decreased small amount to achieve 30 of 2o ～ . To the examination of this kind of problem, wait with general callipers measure a tool to often discover hard, use supersonic thickness gauge to just can be measured only right now piece.

2, hardness exceeds bid
Hardness exceeds the generation of mark issue, basically be the method that as a result of the issue of heat treatment technology after figuration its solve be have heat treatment again with right heat treatment technology. This problem can be solved commonly.

3, material and the limitation that in machining a process, produce
This kind of question is the biggest to the safe harm of device. The examination rises to compare a trouble again. The ingredient that produces limitation also is compared more quite complex, the drawback that it has material itself already has the defect that the incorrect place that machines workmanship problem and heat treatment craft causes again. So the harm that why they produce safety to go up, where is the happening that how avoids this kind of problem? It is with 3 now the exemple is right this one by one does one analysis.

1, the problem of raw material
We know, to bearing high temperature high pressure is reached combustible explode easily for the pipe fitting of medium. The quality of raw material how, the quality that affects pipe fitting directly is used at making the tubal material of this kind of pipe fitting, to carbolic steel tube, majority uses GB531 0, 85 " high-pressured boiler uses seamless steel tube " , GB6479, 86 " fertilizer facilities uses high-pressured seamless steel tube " GB9448, 88 " oil cracking uses seamless steel tube " and GB81 63, 87{carries a fluid to use seamless steel tube " the material that waits for standard regulation. To this kind of steel tube, steelworks should chase a root to have hydraulic test to its. To large and medium-sized for steel, often use vortex flow or supersonic cross flaw detection (UT) replaces hydraulic check, if press country and relevant specification strictly to examine, provide the quality of material or can ensure. But sometimes hard to avoid can appear leakage check, by accident check, have more very person because channel of tubal material stock with goods is jumbly, some entered current field without examining raw material at all, accordingly, to arriving the tubal material after is not the material that batch purchases directly from steel tube factory especially. Divide outside answering to undertake be reinspectinged in the round by the standard, still should raise reinspected rate, chase an examination even but. Many when had contacted from us pipe fitting that has dimensions makes extensive investigation look, a lot of manufactories provide material to what purchase reinspect guard a pass lax, believe the outgoing quality certificate from material blindly (notable is, the true bogus of certificate of some outgoing quality exists problem) , and only the pipe fitting that the visual examination of material of double mound canal uses these unqualified canal material to be made, its quality gets assuring hard. Together with is current of a lot of manufactories examine method both neither is advanced not quite perfect, because this has some of unqualified pipe fitting,serve as eligible product very easily to leave factory.

2, treatment technology issue
At present the treatment figuration of domestic mill business uses commonly below a few kinds of means:
(1) Leng Chong presses figuration;
(2) heats up strike out form;
(Figuration of 3) oil pressure

The problem between the common pipe fitting quality in construction reachs a means of settlement
Metallographic of face of cliff of 3 inside and outside organizes bigger to the diameter, wall thick 3 thicker for, use more from the back method of two kinds of figuration, and the figuration time of these two kinds of methods needs 1 ～ 2 minutes commonly, even some can amount to 3 minutes. Between these a few minutes, how to maintain the relative stability of temperature, crucial question is for the quality to pipe fitting, if temperature difference is too big, can cause steel fibre flow disequilibrium, especially larger to be out of shape position. Because its produce bigger plasticity to be out of shape, if temperature crosses small conference,cause cold make sclerotic appearance and produce brittleness to destroy.

3, the heat treatment after figuration
The final heat treatment after 3 figuration can improve the mechanical performance of steel significantly. Especially for 3 not quite advanced to machining a method manufactories, the heat treatment system with right choice and craft especially important. In GB12459, the carbolic steel pipe fitting that 90" steeliness does not have cold figuration of R of the regulation in seaming pipe fitting to solder should have normalizing or anneal heat treatment. So choose which kind of heat treatment after all, select system of which kinds of anneal especially had better, the choice is not had in the standard or explain, this should decide according to workmanship. The author thinks, no matter select which kind of heat treatment systems,its purpose improves the mechanical performance of pipe fitting namely, increase its strength. Pipe fitting is in cold extrusion process, the plasticity that because its are bigger,the organization of steel meets is out of shape and produce very big change, be like; Banded structure slippage of amlposition of bulky, crystal boundary, interface waits apparent, grain a moment. The change of these textural has very big effect to the cutting treatment of steel and performance characteristics. Want to overcome these adverse change to should pass heat treatment to change the constituent structure that these changed thoroughly, make its grain is refined, the organization is even. Want to achieve this one goal, the complete anneal craft in must using normalizing or anneal will come true. A lot of pipe fitting make a firm and realise this not completely. Stem from some kind of consideration, they undertook aiming to eliminate the anneal heat treatment of stress to the pipe fitting after figuration only, and this kind of anneal not from go up at all the metallographic organization that changes pipe fitting and function, also assure the quality of pipe fitting hard.

4, before pipe fitting leaves factory, reach after arriving examine
Ensure to regarding as last working procedure of pipe fitting quality, examine acting important role, especially for the pipe fitting that to bearing high temperature high pressure reachs combustible and virulent medium, examine the process is attached most importance to especially should. Current, exterior dimension, hardness, ply and magnetic particle flaw detection undertake more before pipe fitting leaves factory (flaw detection of MT) , ultrasonic (the examination of UT) , from undertake examining will look to arrived pipe fitting, the problem appears most is magnetic particle flaw detection and ultrasonic flaw detection examine. To magnetic particle flaw detection, the manufactory uses magnetism yoke method more () of carbolic steel pipe fitting. But because accept equipment restriction, this kind of method mostly the outside face of pipe fitting of bureau be confined to, and the problem appears most just is the wall in pipe fitting, the crackle that often appears to this one part especially the crackle of wall of small diameter pipe fitting, should using magnetism good way or eddy current law to undertake ultrasonic flaw detection examines examining is one has what ask very high to examine to equipment and technology project, because,this is:

(1) it asks handlers is due higher technology and rich experience, it is to checking the blemish that go out to should give those who attribute crackle or other Qi fall decide, accomplish do not leak check, not miscarriage of justice.
　　
(2) it to detecting equipment asks to compare to probe especially tall, larger to a lot of is out of shape position (the two shoulders ministry like 3) reach a diameter to be in the pipe fitting under DNS0mm, majority examines it is easy that homebred straight probe will examine occurrence leakage check, cannot examine to carry out discovery through the spot even, to these difficulty of above, use a diameter to be in the macle probe under 10mm, with crossing inclined enter a law, the effect is better.

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