1、THE ENGINEERING EQUIPMENT AND MATERIALS USERS ASSOCIATION ON-LINE LEAK SEALING OF P If ING: GUIDE TO SAFETY CONSIDERA TiONS EEMUA PUBLICATION No 199 : 2000 AMENDMENTS No I, NOVERIIBER 2002 Tlie aniendiiients set out below are autliorisecl by tlie EEMUA Piping Systems Teclinical Cominittee wliicli li
2、as responsibility for tlie maintenance of this publication. 1/1 Page 4, Section 3 Risks Arid new paragraph: g) Degradation of a pipe within a leak sealing repair clamp niay reduce the pipe wall to an extent where tlie remaining thickness can no longer resist tlie piping system loads (e.g. axial load
3、 due to pressure, theriiial expansion loads, weight of tlie clamp). This niay result in structural failure of the pipe if tlie repair clamp is designed only to seal tlie leak and not to provide strengthening of the pipe. 112 Page 5, siibsectioii 4.1.5 In the first sentence, after joint iraert: or pi
4、ping 1/3 Page 5, siibscctioii 4.1.8 In the second sentence, after bolting insert: and any structural restraint. 114 Ibirl. Acid new second paragraph (rest of subsection unclianged): Tlie design of the clamp should take into account the pipe size and geometry (e.g. ovality). It is important to consid
5、er the ability of the remaining pipe wall thickness to accommodate tlie imposed axial and other loadings, particularly where ongoing internal metal loss is likely. EEMUA 12.1 1.02 STD-EEMUA PUB NO 199-ENGL 2000 5766734 0002934 193 m THE ENGINEERING EQUIPMENT AND MATERIALS USERS ASSOCIATION ON-LINE L
6、EAK SEALING OF PIPING: GUIDE TO SAFETY CONSIDERATIONS PUBLICATION No I99 : 2000 I EEMUAI STD-EEMUA PUB NO L99-ENGL 2000 57bb734 0002935 O28 = THE ENGINEERING EQUIPMENT AND MATERIALS USERS ASSOCIATION ON-LINE LEAK SEALING OF PIPING: GUIDE TO SAFETY CONSIDERATIONS PUBLICATION No 199 : 2000 Copyright O
7、 2000 The Engineering Equipment and Materials Users Association ISBN O 85931 121 X 45 Beech Street LONDON EC2Y 8AD Telephone: 020 7628 7878 Fax: 02076287862 e-mail: saleseemua .co.uk website: www.eemua.co.uk I EEMUAI STDmEEMUA PUB NO 199-ENGL 2000 57bb734 000291b Tb4 = THE ENGINEERING EQUIPMENT AND
8、MATERIALS USERS ASSOCIATION The Engineering Equipment and Materials Users Association-EEMUA-was formed in 1983 by the Amalgamation of the Oil Companies Materials Association (OCMA) and the Engineering Equipment Users Association (EEUA). It is an organisation of substantial purchasers and users of en
9、gineering products, whose members include leading national and multi-national companies in the petroleum, gas, 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 is concerned with the desig
10、n, installation, operation and maintenance of the engineering plant used by members in pursuing their business 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 technological developments and im
11、prove the effectiveness and efficiency of their engineering activities. EEMUA supports the British Standards Institution, works with other institutions, associations, government departments, regulatory authorities and the Confederation of British Industry, and is also actively involved with other st
12、andards-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 primarily for members use, but ar
13、e usually offered 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 list of current EEMUA Publications which may be purchased from the Associat
14、ion is given at the end of this document. Full Members Associate Members Associated Octel BG BP Ammo Conoco Dow Corning Eastern Generation Eutech Foster Wheeler Energy EssoExxonMobil Lindsey Oil Refinery National Power PowerGen Shell As tr fineca BASF D&C Engineering/MERCON Netherlands Elf Explorati
15、on UK Flexsys Phillips Petroleum UK Pilkington Technology Royal Vopak Netherlands Texaco UOP 1 ABOUT THIS PUBLICATION: LEGAL ASPECTS In order to ensure that nothing in this publication can in any manner offend against or be affected by the provisions of the Restrictive Trade Practices Act 1976, the
16、recommendations which it contains will not take effect until the day following that on which its particulars are furnished to the Office of Fair Trading. As the subject dealt with seems likely to be of wide interest, this publication is also being made available for sale to non-members of the Associ
17、ation. Any person who encounters an inaccuracy or ambiguity when making use of this publication is asked to notify EEMUA without delay so that the matter may be investigated and appropriate action taken. It has been assumed in the preparation of this publication that the user will ensure selection o
18、f those parts of its contents appropriate to the intended application and that such selection and application are correctly carried out by appropriately qualified and experienced persons for whose guidance the publication has been prepared. EEMUA does not, and indeed cannot, make any representation
19、or give any warranty or guarantee in connection with material contained in its publications, and expressly disclaims any liability or responsibility for damage or loss resulting from their use. Any recommendations contained herein are based on the most authoritative information available at the time
20、 of writing and on good engineering practice, but it is essential for the user to take account of pertinent subsequent developments or legislation. All rights are reserved. No part of this miblication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means: electr
21、onic, mechanical, photocopying, recording or other. Infringement of copyright is not only illegal, but also reduces the Associations income thereby jeopardising its ability to fund the production of future publications. iii STD*EEMUA PUB NO L77-ENGL 2000 = 5766734 O002738 837 CONTENTS Page FOREWORD
22、1 1 INTRODUCTION AND SCOPE . 3 2 LEAK SEALING TECHNIQUE . 3 3 RISKS 3 4 PREPARATION . 4 4.1 RiskAssessment 4 4.1.1 General . 4 4.1.2 Nature and Cause of Leak 4 4.1.3 Extent of Damage . 4 4.1.4 Operating Conditions . 4 4.1.5 History: Leak Records, Bolt Re-tightening and/or Previous Leak 4.1.6 Conditi
23、on of Piping, Bolting and Gaskets 5 4.1.7 Contents of Piping System . 5 4.1.8 Clamp Design . 5 4.1.9 Valve Glands 6 4.1.10 Site Access . 6 4.1.11 Other Considerations . 6 4.2 Work Authorisation 7 Sealing . 5 4.3 Emergency Procedures . 7 5 EXECUTION . 7 6 FOLLOW-UP . 7 EEMUA PUBLICATIONS-SUMMARY LIST
24、 . 9 V Previous page is blank STD-EEMUA PUB NO 199-ENGL 2000 I 57bb734 0002919 773 = FOREWORD Although certain companies may have their own guides to on-line leak sealing of piping, there is, as far as is known, no publicly available document containing advice on the pertinent safety factors that ne
25、ed to be considered in preparing for and executing the technique. The present Guide has accordingly been developed by the EEMUA Piping Systems Technical Committee to meet this perceived need. It should be noted that the term piping includes valves. 1 STD-EEMUA PUB NO L99-ENGL 2000 5766734 OOOZ92O 49
26、5 = 1 INTRODUCTION AND SCOPE Certain leaks from pressurised piping may be effectively contained by on-line sealing methods involving injection of elastomeric compounds. The methods, originally developed for application to leaking steam or condensate systems, may also be applied to process piping lea
27、ks but additional precautions are usually necessary. Because of the inherent risks, such methods should only be carried out by trained personnel working to an agreed procedure. Also, since leakage indicates deterioration of the pressurecontaining material, all repairs by these methods should be rega
28、rded as temporary. It is therefore essential that records of such repairs are maintained. This publication is applicable to industrial piping in which leaks are to be temporarily sealed whilst in service by the injection of a suitable compound. It gives guidance on the limits of application of the t
29、echnique, the factors to be considered when evaluating the feasibility of its use, and the preparation and execution of the procedure. It also provides the information necessary for an appropriate multi-skills team to conduct a detailed risk assessment in order to decide whether the technique should
30、 be applied in a particular case. Injection techniques should not be used for the repair of cracks as effective penetration by the sealant is unlikely to be achieved. Neither are the techniques suitable for repairs to special joints such as those employing pressure energised gaskets or lens rings. I
31、n these cases the sealant pressure may affect the alignment of the gasket or lens ring and cause the joint to fail. 2 LEAK SEALING TECHNIQUE A temporary repair by leak sealing normally involves one of the following: a) b) c) installation of injection nozzles into a valve packing area fitting caulkin
32、g wires, bands or simple clamps on the perimeter of flanges for retaining injection compound, together with injection nozzles purpose built clamps and boxes. 3 RISKS Leak sealing techniques involving the injection of elastomeric compounds frequently require the use of injection pressures greater tha
33、n the design pressure of the component that is leaking. In addition, an on-line modification to the pipework is necessary to enable injection to take place (e.g. fitting a clamp box, drilling a valve stuffing box). Hazardous incidents can result from the over pressurising or overloading of equipment
34、 during leak sealing operations. The following are examples of such incidents.- Caulking compounds, wire and shaped inserts used to retain injected sealing compound may be ejected by the line and sealant pressure causing injury to personnel and damage to equipment. Clamps and boxes around the leakin
35、g area may fail catastrophically under product and sealant pressure, creating projectiles which may injure personnel and damage equipment. a) b) 3 Previous page is blank STD-EEMUA PUB NO 399-ENGL 2000 m 57bb73Li 0002923 321 m The hammering of wire and shaped inserts between flanges may significantly
36、 overstrain individual bolts leading to sudden failure of all bolting, and catastrophic failure of the equipment joint. Injecting sealant under a clamp or caulked wire around the circumference of the flange may result in temporary increase of the axial load on flange bolting which may cause bolting
37、failure. The pressure of the injected compound, or the weight of the clamp, may be sufficient to cause failure or collapse of the piping, particularly if corroded. Drilling into a valve stuffing box may result in a leak at full line pressure if the valve packing is in poor condition. 4 4.1 4.1.1 4.1
38、.2 4.1.3 4.1.4 PREPARATION Risk Assessment General As described in the previous section, carrying out temporary repairs to leaking equipment can be a potentially hazardous operation. Consequently the utmost care needs to be taken when considering, planning and executing a job. A risk assessment shou
39、ld first be made by the plant engineer in consultation with the Operations department and the leak sealing contractor. Such an assessment should take into account the factors set out in 4.1.2 to 4.1.11 below. Nature and Cause of Leak It is important to determine the cause of the leak. For example, a
40、 leaking flange joint may be due to gasket failure or to bolt relaxation. The factors causing the leak may increase the possibility that the leak sealing operation results in failure of the equipment. In addition, the likelihood of further deterioration of the pipework after leak sealing should be a
41、ssessed. Extent of Damage It is important to establish the full extent of the damage to the equipment prior to determining the suitability of a particular type of repair. This may involve establishing the thickness of adjacent material, the presence of any cracking, corrosion of the bolting, deterio
42、ration of the gasket etc. Operating Conditions Process operating conditions have a major influence on the suitability of repair by sealant injection. Normal operating pressures and temperatures, cyclic conditions, and shutdown or upset conditions should be taken into account. Reductions in temperatu
43、re and pressure during the repair are generally beneficial. 4 STD*EEflUA PUB NO 1i99-ENGL 2000 W 57bb734 O002922 268 W 4.1.5 History: Leak Records, Bolt Re-tightening and/or Previous Leak Sealing A history of bolt re-tightening or sealant re-injection may indicate deterioration of a joint, requiring
44、 remedial action. If it is found necessary to re-inject sealant, consideration should be given to shutting down and effecting a permanent repair. It is prudent to check with local supervisors, operators, and maintenance staff for general information on plant item history, particularly as bolt re-tig
45、htening may not have been recorded. 4.1.6 Condition of Piping, Bolting and Gaskets Consideration needs to be given to the possibility of corroded and eroded piping, flanges and bolts, particularly where re-injection at a previously sealed leak position is contemplated. As a precaution against failur
46、e, the condition of piping, flanges, bolting and gaskets should be confirmed and assessed as being suitable for the leak sealing operation. It is common for the bolting to be replaced in a controlled manner prior to leak sealing (see EEMUA Information Sheet No 17, Pub. 195 Compendium of EEMUA Inform
47、ation Sheets on Topics Related to Pressure-Containing Equipment). Where this is impractical, the bolts should be visually examined, supplemented where possible by ultrasonic or other nondestructive examination. When a joint leaks, it is possible for an environment to develop within the joint which p
48、romotes stress corrosion cracking of the bolting material. For example, in steam/ feedwater duties, free caustic can concentrate to levels sufficient to induce caustic embrittlement (cracking) of common bolting materials. Other factors that can affect bolting are: a) poor supporting of piping b) ext
49、ernal dynamic loads c) fatigue due to vibration. In assessing the condition of gaskets, the type, age, and service conditions should be considered. 4.1.7 Contents of Piping System It is important to check the chemical compatibility of the clamp or band and sealing compound with the fluid inside the piping system. Incompatibility could lead to problems such as corrosion of the clamp or band, degradation of the sealant (rendering it ineffective), and contamination of the fluid stream. The nature of the process fluid (toxicity, flammability) will determine the need for
