Use than by welding materials of low melting point metal melting point solder.doc

Use than by welding materials of low melting point metal melting point solder, after heating the solder to melt, by capillary action will solder inhaled into the clearance joint interface, wetting the metal surface, formed between the solid phase liquid diffusion brazing welding head. (4) stud welding The stud end with the panel (or pipe) electric arc surface contact, after waiting for the contact melting, add some pressure on stud welding method. LNG top moistureproof layer plate lateral peg to welding a lot of concrete. Adopt the method of stud welding can improve efficacy of more than ten times. (5) other welding methods Electron beam welding, laser welding, flash butt welding, ultrasonic welding, friction welding, the explosion welding, electroslag welding, high frequency welding, gas welding, pressure welding, cold welding, diffusion welding, etc. Second, the welding procedure qualification (a) welding procedure qualification and its function In products: 1. The welding procedure qualification before welding, the welding process of preliminary to formulate detailed rules for the card or other disciplines in the welding process for confirmatory test. By preparing the welding process, close to the actual production conditions, made from materials, process parameters and the same simulation welding test plate products, and according to the product technical conditions on the test plates. 2. If all the related indexes accord with technical requirements, then prove to welding process is feasible, at this time can be formal welding process according to the welding procedure qualification report detailed rules for the card, to guide the actual welding products. 3. If there is an inspection items index of unqualified, suggests that the welding process can not be used in production, need to make corresponding modification or renegotiated later, again to do welding procedure qualification test. 4. Welding procedure qualification: used to verify and assess the correctness of the welding process, the assessment report is not direct production directly, is welding process conditions supporting documents (card), the same welding procedure qualification report can be used as the basis of a few welding process card. 7 P059 (2) the welding procedure qualification According to the specific requirements of different products and welding procedure qualification, according to the provisions of the corresponding evaluation criteria for evaluation. (3) the welding procedure qualification steps 1. Preparation of welding procedure qualification a power of attorney. 2. To formulate welding way, factors to consider include: (1) physical properties of parent metal, for example, now 9% nickel steel is generally used to LNG tank (also has 9 called nickel steel, chemical formula for 06 nickel 9 Dr, cryogenic vessel steel) due to its magnetization characteristic, in using ordinary when welding, welding inverter will appear the phenomenon of magnetic blow. So according to the physical properties of 9% nickel, appropriate chooses degaussing characteristics of welding machine for welding. Amorphous tree fat such as ABS/PC, PVC, P milli ma and PES; Half a crystalline resin such as HDPE, PA, PP, the welding of TPO appropriate USES vibration welding. (2) the chemical properties of parent metal, such as the chemical activity of the titanium and titanium alloy, vulnerable to oxygen, nitrogen, such as pollution, so cant adopt manual welding, co2 gas shielded welding, welding method, etc. Now commonly used is argon arc welding, submerged arc welding and vacuum electron beam welding. Magnesium alloy, alloy steel and aluminum melt welding with tungsten and inert gas protection welding. (3) the stress of the weld, such as plate lap weld generally as seal welding, the welding seam bending resistance is poorer, the welding of tank bottom plate is used more in this form, this kind of welding with manual arc welding and co2 gas shielded welding. (4) the welding part geometry, structure of large or heavy components, for example, the rules of the weld and filling amount is larger, appropriate USES automatic submerged arc welding. For thin plate welding and weld, appropriate USES resistance welding. (5) the welding position, overhead welding seam should be taken, for example, cannot use submerged arc welding. 3. According to the provisions of the welding procedure qualification standards or design documents for welding process instructions or qualification plan, preliminary process. After welding method, it is necessary to make welding process parameters. Each are not identical, the kinds of welding process parameters, such as manual welding mainly includes: electrode model (or brand), the diameter, the type of current, voltage, welding power source, polarity connection, welding layer number, number, inspection methods and so on. 4. According to the welding process instructions (or preliminary process) for specimen preparation, welding, weld inspection (heat treatment), sample processing, sample. 5. The use of performance evaluation according to the requirements. If the assessment is unqualified, should be to modify the proposed welding process instructions or preliminary process, to assess. 6. Finishing welding records, test report, preparation of welding procedure qualification report; Assessment report shall record in detail the process, the welding parameters, test results and test data and evaluation conclusion, upon examination and approval by the welding engineer, unit technical managers approval, in the technical documents. 7. Based on welding procedure qualification report, combined with welding construction experience and the actual conditions of preparation of welding procedure specification and welding working instruction, process card, welding shall be in strict accordance with the provisions of the welding work instruction or process card for welding. (4) welding procedure qualification requirements 1. General requirements (1) welding procedure qualification should be based on reliable steel welding performance, and up until completion of the works. Welding parameters used in the welding procedure qualification, in principle is according to the weldability of the steel welding test result to determine, especially after the heat input, preheat temperature and hot temperature. For weldability have been fully understood, there is a clear guidance of welding process parameters, and has long use in practice production in domestic and foreign mature steel grade, generally do not need to be done by construction enterprises weldability test. For domestic development and production of new steel grades, or imported from abroad without used types of steel, should be provided by the steel weldability test assessment data. Otherwise the construction enterprises should collect related data and weldability test, as the basis of welding procedure parameters. 8 P060 (2) equipment, instrument used in the welding procedure qualification should be in normal working state, steel, welding materials must conform to the corresponding standards, skilled welding by this unit into the member to use this unit welding equipment welding specimen. (3) management assessment work and comprehensive evaluation of welding and test results of personnel should be the welding engineer. (4) after finishing the assessment data should be stated, and by the welding engineer to confirm the results. (5) after the examination and approval of the assessment data can be in the same quality management system in general. For example, the basi