1、THE ENGINEERING EQUIPMENT AND MATERIALS USERS ASSOCIATION RECOMMENDATIONS FOR TUBE END WELDING: TUBULAR HEAT TRANSFER EQUIPMENT (Part 7 - Ferrous Materials (formedy OCMA Spefication No. TEW 1) PUBUCAIION No. 143 I EEMUAJ RECOMMENDATONS FOR TUBE END WELDING: TUBULAR HEATTRANSFER EQUIPMENT (Part 7 - F
2、errous Materials (formerly OCMA Specification No. TEW 1 J PUBUCATION No. i43 Copyright 1985 The Engineering Equipment and Materials Users chemical and energy industries. A list of Full and Associate Members (the latter being limited to membership of three technical committees) is given below. EEMUA
3、is concerned with the design, installation, operation and maintenance of the engineering plant used by members in pursuing their bu$ness activities. The Association aims to reduce members costs by providing the opportunity for them to share resources and expertise in order to keep abreast of technol
4、ogical developments and improve the effectiveness and efficiency of their engineering activities. EEMUA supports the British Standards Institution, works with other institutions, associations, government departments, regulatory authorities qd the Confederation of British Industry, and is also active
5、ly involved with other standards-making bodies, both national and international, such as the American Petroleum Institute. Work, which is carried out in-house by members alone or with the help of other organisations, may lead to the production of Association publications. These are prepared primaril
6、y for members use, but are usually ofred for sale and thus for more general use. Such publications may also be submitted, normally through the British Standards Institution, as bases for appropriate national, European or international standards. A iist of current EEMUA Publications which may be purc
7、hased from the Association is given at the end of this document. Full Members Associate Members Associated octel BG BP Amm Caltex Petroleum Conoco Dow corning Eastern Generation EssolExxonMobil hwh Foster Wheeler Energy Lindsey Oil Refinery National Power PowerGen Shell AsraZeneca BASF D by welded j
8、oint, it is meant that the type of leaktight welded tube to tube plate joint considered in this specification, is intended to provide for the support of ail loads envisaged and not merely a seal to prevent leakage at the end of the expanded tube. It was the opinion of that meeting that an urgent nee
9、d existed for standardised procedures to be established for the design, fabrication, inspection and testing of these and simiiar components. There being no national or intenationai standard in existence which covered adequately this important subject, members agreed to pool their knowledge and exper
10、ience, and to co-operate in preparing a recommended practice for Tube End Welding and Testing. Such a recommendation could then be use as a basis for specifying requirements for the oil, chemical and other industries. This advisory document which is in SI units summarises the findings of the working
11、 group at the present time. After a period of circulation within inudstry, it is intended that these preliminary recommendations be subject to a complete review and the format rearranged to give a final presentation in three parts as follows: - PART1 : (a) GENERAL (b) FERROUS MATERIALS PART 2 : NON-
12、FERROUS MATERIALS PART3 : MISCELLANEOUS This document was produced under the auspices of the OCMA Welding Panel with the assistance of representatives of the Heat Transfer Society. , The Member Companies of OCNIA expressly declare that they are completely at liberty to buy goods which do not comply
13、with this specification whenever they desire to do so. . . 0.26%) steel C.% Mo ) 1% Cr. % Mo. ) I% Cr. % Mo. ) 2% Cr. 1% Mo. ) 46% Cr. % Mo. ) No preheat * 50C. min 100C. min 200C. min 18% Cr. 8% Ni. None * * No welding is permitted if the plate temperature is below 5C. These preheat temperatures ar
14、e appropriate when using filler metal of matching composition; when austenitic filler metal is used, the preheat may be substantially less and shall be established in the procedure test. The preheat and interpass temperature used in production shai be, within practical limits, the same as that used
15、in the procedure test. Experience has shown that because of the increased restraint offered by the larger assembly, the preheat necessary in production may exceed the minimum necessary to obtain satisfactory welds in the procedure test. For this reason an allowance should be made for this effect in
16、determining the preheat temperature chosen for the procedure test. Temperatures shaU be measured preferably by contact pyrometer; alternatively temperature indicating crayons may be employed, care being taken not to contaminate welding zones. In the event of welding being interrupted, the weld joint
17、 shall be insulated and allowed to cool slowly if the interpass temperature is not maintained. Before welding is resumed, the section to be welded shall be brought back to the required preheat temperature. When welding is completed, the joint shall be allowed to cool slowly 0000b82 105 m -6- 7.4 Ele
18、ctrical means of preheating shali be used wherever possible. Fixed gas bumers may be used for preheating and maintaining the preheat, provided that an adequate degree of control can be demonstrated. 8. WELD I NG s 8.1 8.2 8.3 8.4 The tubes shall be welded to the tube plate using the approved procedu
19、re (Ciause 3). Welding shail be canied out preferably in the flat position, i.e. with the tube plate horizontal. Welding with the tube plate vertical shall also be permissible where practicable, but attention is drawn to the difficulty of ensuring uniform throat thickness around the periphery of the
20、 weld. Welding with the tube plate in any other pasition shall also be acceptable provided it is proven by procedure test. Any over- or spillage of weld metal into the bares of the tubes which is considered detrimental shall be cleaned out and spatter removed. AU tubes shall be welded indvidualiy. S
21、uch procedures as figure 8 welding and other complex welding patterns are not recommended. The tube joints shail be welded in such a manner as to minimise distortion of the tube plate. Unless oth a low pressure air test or, preferably, by a gas leak test (see Clauses 12.2, 12.3 and 12.4). For both t
22、ypes of test, the tube bundle shall be placed in the shell and welded or bolted as designed and all openings blanked off. No liquid shall be applied to the shell side of the tube plate prior to any gas leak test. Where manual multi-run welds are used there is an obvious advantage, particularly for h
23、eat exchangers for critical duties, in carrying out a leak test on the completion of the first runs only of all tube to tube plate welds on both tube plates. 12.2 Air Testing The assembly shall be tested for leaks by applying a pressure of 0.5 bar. High presnue tests are not generally favoured due t
24、o the hazards of stored energy especially when volumes are large. While the shell is under pressure a simple soap or detergent test shall indicate escapes of ak from leaks. Generally, a 2% solution by volume of an appropriate foaming agent in water is effective. Testing is also permissible employing
25、 aidnitrogen gas mixtures. 12.3 12.4 . , Gas leak Testing Where greater sensitivity to leaks is required, a tracer gas leak test is preferred to an air test. The use of helium, hydrogen or argon as the tracer gas is permissible, but for reasons of economy, argon is preferred. The sniffer gun or dete
26、ctor, which is sensitive to any gas having a thermal conductivity different from that of air, usually has several ranges of sensitivity however for certain senrice duties, e.g. where possible crevice corrosion or vibration fretting susceptibilities must .be minimised, it may be necessary to provide
27、for intimate contact between the O.D. of the tubes and the bores of the tube plate holes. This may be accomplished by light expansion after both welding and successful leak testing (see Clause 12) but before pressure testing (see Clause 15); where however no crevice corrosion at all is permissible,
28、the recommended joint detail is as shown in Appendix A, Sheet 5, Figs. 6A and 6B. 14.2 Tube expansion after welding shall lie within the zone from approximately 10 mm from the weld junction to 3 mm from the back of the tube plate. 14.3 The equipment used for tube expansion shall be of the mandrel an
29、d parallel rolier type incorporating limiting controls to give a predetermined amount of tube wall thinning, e.g. controlled torque equipment. 14.4 The amount of tube wall thinning shall be 5-7%* of the original tube wall thickness and the machine settings to achieve this thinning shall be determine
30、d and checked during procedure testing by micrometer measurements as follows: Diameter of tube hole: “D I . Mean outside diameter of tube: “d I .-. Difference : “D-d“ . . Inside diameter of tube after expansion: “T I . Inside diameter of tube before expansion: t 11. 41 Il Difference: “T-t“ . . . (T-
31、t) - (D-d) 2 Tube wall thinning = * See References. Item 5. - 10 - 14.5 if the tubes are to be expanded after welding, the bores shall be inspected for evidence of distortion and/or weld spillage. It is permissible to lightly dress the bores to avoid jamming of the rollers during subsequent expansio
32、n; but care must be exercised to ensure the minimum removal of metal from the bores of the tubes. By agreement, special techniques such as the insertion of tapered ceramic plugs in the bores, may be applied during welding to prevent weld spillage. 15. PRESSURE TESTING 15.1 The tube piate face, the w
33、elds and the internal surfaces of the tubes to a length of about 13 mm shal be thoroughly cleaned by a suitable method; any Tease present shali be removed either by the use of a solvent or by steam jets. A coating of whitewash may then be applied to assist in detecting leaks. 15.2 me final acceptanc
34、e pressure test shaii be conducted at the design test pressure. Ciean kerosine may be used and is more searching when hydrophobic residues such as oil or grease are present but attention is drawn to the risk of fire*. If water is used, it is recommended that 2% by volume of an approved wetting agent
35、 or detergent should be added. “he dace tension of a 296 detergent solution is about 30 mN/m compared with plain water at 75 and kerosine at 25 mN/m. The possible risk of crrosion by the use of detergent is minimised by the careful selection of additions and control of the amount used. Detergents ar
36、e also available which carbonise at low temperature of the order of 150C. The addition of 0.2% sodium nitrite to the water is recom- mended as a corrosion inhibitor; if austenitic materiais are used the chloride content of the water should not exceed 30 p.pm.* Wh Use0 ONLY WHRE me WALL TWICKNWS ADEQ
37、UATE - .L-MIN FIG. 6A APPENDIX A - SHEET 5 FIG. 66 NOTE2 DURfN - d t- a! G Z W E r) G1 P al +- ta II t- crl .- I c) Q w T. d O b u? t- n w I- d U t I U 4 n a a! r: a i.I cf a 3 U cl, Fo tl - U lL O STD-EEMUA PUB NO LLi3-ENGL 1985 W 57bb73i1 0000b77 409 m APPENDlX c. SHEET 7 SUPPOQT RI NO-. LOA0 13 A
38、PPLIED SLOWLY TO ENSUR NO SHOCK COADINe 13 APPLIED & TEST CONTINUED UNTIL FAILURE Oc TU0E WELO UWULTS. STD-EEMUA PUB NO 3iq3-ENGL 1985 D 57bb73rl 0000700 T50 H APPENDIX C SHEET 3 ,- 24 - MANUFACTURERS RECORD OF WELDING PROCEDURE QUALIFICATION TEST Manufacturers Name Address Welders Name Date of Test
39、 Plate Materiai Specification Tube Material Specification Welding Procesr Electrode or Filler No. of Runs Weling Conditions Joint Detail (Sketch) : ClassificationBrand Name Identity No. Test No. Thickness Dia/Thickness Pitch shielding Gas Dia. Reheat Welding Position Other Data ASSESSMENT OF RESULT Test Remarks 1. Visual Surface appearance, profile, etc. Macrosection. 2. Radiography 3. Tear or Weld Strength (if specified) RESULT OF TEST : PASSFAIL Test supervised by Manufacturers Stamp & Date Laboratory Test by inspecting Authority Stamp and Date
