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1、MANUAL PROTECTIVE STEAM HEATING OF PIPING SYSTEMS DEP 31.38.30.11-Gen. December 1997 DESIGN AND ENGINEERING PRACTICE This document is confidential. Neither the whole nor any part of this document may be disclosed to any third party without the prior written consent of Shell International Oil Product
2、s B.V. and Shell International Exploration and Production B.V., The Hague, The Netherlands. The copyright of this document is vested in these companies. All rights reserved. Neither the whole nor any part of this document may be reproduced, stored in any retrieval system or transmitted in any form o
3、r by any means (electronic, mechanical, reprographic, recording or otherwise) without the prior written consent of the copyright owners. PREFACE DEP (Design and Engineering Practice) publications reflect the views, at the time of publication, of: Shell International Oil Products B.V. (SIOP) and Shel
4、l International Exploration and Production B.V. (SIEP) and Shell International Chemicals B.V. (SIC) The Hague, The Netherlands, and other Service Companies. They are based on the experience acquired during their involvement with the design, construction, operation and maintenance of processing units
5、 and facilities, and they are supplemented with the experience of Group Operating companies. Where appropriate they are based on, or reference is made to, national and international standards and codes of practice. The objective is to set the recommended standard for good design and engineering prac
6、tice applied by Group companies operating an oil refinery, gas handling installation, chemical plant, oil and gas production facility, or any other such facility, and thereby to achieve maximum technical and economic benefit from standardization. The information set forth in these publications is pr
7、ovided to users for their consideration and decision to implement. This is of particular importance where DEPs may not cover every requirement or diversity of condition at each locality. The system of DEPs is expected to be sufficiently flexible to allow individual operating companies to adapt the i
8、nformation set forth in DEPs to their own environment and requirements. When Contractors or Manufacturers/Suppliers use DEPs they shall be solely responsible for the quality of work and the attainment of the required design and engineering standards. In particular, for those requirements not specifi
9、cally covered, the Principal will expect them to follow those design and engineering practices which will achieve the same level of integrity as reflected in the DEPs. If in doubt, the Contractor or Manufacturer/Supplier shall, without detracting from his own responsibility, consult the Principal or
10、 its technical advisor. The right to use DEPs is granted by SIOP, SIEP or SIC, in most cases under Service Agreements primarily with companies of the Royal Dutch/Shell Group and other companies receiving technical advice and services from SIOP, SIEP or SIC. Consequently, three categories of users of
11、 DEPs can be distinguished: 1)Operating companies having a Service Agreement with SIOP, SIEP, SIC or other Service Company. The use of DEPs by these Operating companies is subject in all respects to the terms and conditions of the relevant Service Agreement. 2)Other parties who are authorized to use
12、 DEPs subject to appropriate contractual arrangements. 3)Contractors/subcontractors and Manufacturers/Suppliers under a contract with users referred to under 1) or 2) which requires that tenders for projects, materials supplied or - generally - work performed on behalf of the said users comply with
13、the relevant standards. Subject to any particular terms and conditions as may be set forth in specific agreements with users, SIOP, SIEP and SIC disclaim any liability of whatsoever nature for any damage (including injury or death) suffered by any company or person whomsoever as a result of or in co
14、nnection with the use, application or implementation of any DEP, combination of DEPs or any part thereof. The benefit of this disclaimer shall inure in all respects to SIOP, SIEP, SIC and/or any company affiliated to these companies that may issue DEPs or require the use of DEPs. Without prejudice t
15、o any specific terms in respect of confidentiality under relevant contractual arrangements, DEPs shall not, without the prior written consent of SIOP and SIEP, be disclosed by users to any company or person whomsoever and the DEPs shall be used exclusively for the purpose for which they have been pr
16、ovided to the user. They shall be returned after use, including any copies which shall only be made by users with the express prior written consent of SIOP and SIEP. The copyright of DEPs vests in SIOP and SIEP. Users shall arrange for DEPs to be held in safe custody and SIOP or SIEP may at any time
17、 require information satisfactory to them in order to ascertain how users implement this requirement. All administrative queries should be directed to the DEP Administrator in SIOP. NOTE: In addition to DEP publications there are Standard Specifications and Draft DEPs for Development (DDDs). DDDs ge
18、nerally introduce new procedures or techniques that will probably need updating as further experience develops during their use. The above requirements for distribution and use of DEPs are also applicable to Standard Specifications and DDDs. Standard Specifications and DDDs will gradually be replace
19、d by DEPs. DEP 31.38.30.11-Gen. December 1997 Page 2 TABLE OF CONTENTS 1.INTRODUCTION.4 1.1SCOPE 4 1.2DISTRIBUTION, INTENDED USE AND REGULATORY CONSIDERATIONS4 1.3DEFINITIONS 4 1.4CROSS-REFERENCES5 2.GENERAL. 6 3.DESIGN AND ENGINEERING7 3.1STEAM TRACING.7 3.2STEAM JACKETING.8 3.3SUPPLY AND RETURN SY
20、STEM10 4.DOCUMENTS.13 4.1PROCESS ENGINEERING FLOW SCHEMES13 4.2STEAM TRACING/JACKETING PLAN DRAWINGS13 4.3ISOMETRIC DRAWINGS13 4.4TRACER REFERENCE LIST13 4.5TAGGING 13 5.MATERIALS AND FABRICATION.14 5.1MATERIAL SELECTION.14 5.2PIPING. 14 5.3WELDED JOINTS.14 5.4FLANGED JOINTS14 6.APPLICATION.15 6.1IN
21、STALLATION.15 6.2INSPECTION AND TESTING.15 6.3COMMISSIONING.15 7.PAINTING, PRESERVATION AND INSULATION.16 7.1PAINTING 16 7.2INSULATION.16 8.MAINTENANCE17 9.REFERENCES18 APPENDICES APPENDIX 1TYPICAL ARRANGEMENT OF A STEAM TRACING SYSTEM.19 APPENDIX 2TRACER ATTACHMENT.20 APPENDIX 3STEAM JACKETING22 AP
22、PENDIX 4TRACING OF SMALL BORE VALVES23 APPENDIX 5TRACING OF LARGE BORE VALVES24 APPENDIX 6TRACING OF TRUNNION SUPPORTS25 DEP 31.38.30.11-Gen. December 1997 Page 3 1.INTRODUCTION 1.1SCOPE This DEP specifies requirements and gives recommendations for protective steam heating of piping systems (excludi
23、ng transmission pipelines). This DEP is a revision of an earlier DEP of the same number, dated September 1991. Hot oil and hot water protective heating systems are excluded from the scope of this DEP. Design requirements for steam distribution systems are also excluded from the scope of this DEP. Al
24、so excluded from the scope of this DEP is electrical trace heating, for which DEP 33.68.30.32-Gen. applies. 1.2DISTRIBUTION, INTENDED USE AND REGULATORY CONSIDERATIONS Unless otherwise authorised by SIOP and SIEP, the distribution of this DEP is confined to companies forming part of the Royal Dutch/
25、Shell Group or managed by a Group company, and to Contractors and Manufacturers nominated by them (i.e. the distribution code is “F“, as defined in DEP 00.00.05.05-Gen.). This DEP is intended for use in oil refineries, chemical plants, gas plants and, where applicable, in exploration and production
26、facilities and supply/marketing installations. If national and/or local regulations exist in which some of the requirements may be more stringent than in this DEP the Contractor shall determine by careful scrutiny which of the requirements are the more stringent and which combination of requirements
27、 will be acceptable as regards safety, environmental, economic and legal aspects. In all cases the Contractor shall inform the Principal of any deviation from the requirements of this DEP which is considered to be necessary in order to comply with national and/or local regulations. The Principal may
28、 then negotiate with the Authorities concerned with the object of obtaining agreement to follow this DEP as closely as possible. 1.3DEFINITIONS 1.3.1General definitions The Contractor is the party which carries out all or part of the design, engineering, procurement, construction, commissioning or m
29、anagement of a project or operation of a facility. The Principal may undertake all or part of the duties of the Contractor. The Manufacturer/Supplier is the party which manufactures or supplies equipment, technical documents/drawings and services to perform the duties specified by the Contractor. Th
30、e Principal is the party which initiates the project and ultimately pays for its design and construction. The Principal will generally specify the technical requirements. The Principal may also include an agent or consultant authorised to act for, and on behalf of, the Principal. The word shall indi
31、cates a requirement. The word should indicates a recommendation. DEP 31.38.30.11-Gen. December 1997 Page 4 1.3.2Specific definitions CMCollecting Manifold for steam tracers DMDistribution Manifold for steam tracers leadthe steam line from a DM to a tracer steam trapan automatic device used to remove
32、 condensate from a steam system with a minimum loss of live steam. For terminology and diagrams of steam traps, reference is made to ISO 6704. Tailthe steam line from a tracer to the CM tracersteam heating piping which runs along the process pipe 1.4CROSS-REFERENCES Where cross-references to other p
33、arts of this DEP are made, the referenced section number is shown in brackets. Other documents referenced by this DEP are listed in (9). DEP 31.38.30.11-Gen. December 1997 Page 5 2.GENERAL Heating is usually required if a temperature drop below a particular value would cause: coagulation, crystallis
34、ation, paraffin separation, congealing or hydrate formation; condensation of process gas; process fluids to become too viscous; freezing (and expansion) of water-containing process fluids; brittleness of piping material. The following heating systems are described in this DEP: steam tracing:-permane
35、nt heating -winterising steam jacketing:-fully jacketed -not fully jacketed The heating medium for tracing and jacketing should be saturated low pressure (LP) steam. However, medium pressure (MP) steam may be used. A steam tracer heating system may be: a closed system in which the condensate is coll
36、ected for re-use; an open system in which the condensate is discharged into a drain or soakaway. Tracing steam and condensate headers should be separate from the normal steam distribution and condensate collecting system. For large systems (as defined by the Principal) separate winterising headers s
37、hall be installed to allow the system to be preserved when not needed (e.g. in summer). This is done by closing the condensate valves and leaving the steam valves open. They are then to be flushed before start-up in the winter. Piping in steam service shall be arranged so that condensate accumulatio
38、n is avoided. All steam pipes shall have drain facilities at the low points and at the end to remove condensate (e.g. during commissioning). The requirement for protective heating of piping and instruments shall be indicated on the process engineering flow schemes and on the piping data sheets (see
39、also 4.) DEP 31.38.30.11-Gen. December 1997 Page 6 3.DESIGN AND ENGINEERING 3.1STEAM TRACING In steam tracing systems, the steam tracers are attached to, and insulated together with, the process piping. For insulation, see (7). Steam traced caustic soda (NaOH) lines shall have an insulation layer be
40、tween process line, tracers and fasteners to prevent high temperatures, which would promote caustic stress corrosion cracking of the pipe, at contact points. Carbon steel tracers used on stainless steel process lines shall have isolation blocks (e.g. ceramic board) between the tracer and the process
41、 line. Other process fluids may be sensitive to hot spots from line contact with tracers. Therefore, the process fluid properties and heating limitations shall be checked by corrosion and process engineers. If spot heating is not acceptable, insulation shall be placed between process line, tracers a
42、nd fasteners. The piping data sheets shall mention this specific installation requirement under Remarks. For each steam tracing application, the heat loss shall be calculated. The heat input together with the local weather conditions and the insulation system will dictate the number and size of the
43、tracers per application. Tracers shall be DN 15 or DN 20 seamless steel pipe, schedule 80. Single or multiple tracers are used, depending on pipe size and service. Guidance on the number and size of tracers required for different line sizes and conditions is given in the following table: Table 1Numb
44、er and size of tracers Process pipe nominal diameter (DN) Up to 4050 - 200250 - 300350 - 450500600 Number and size (DN) of tracers Winterising1 x 151 x 151 x 151 x 201 x 201 x 20 Solidification1 x 151 x 151 x 151 x 201 x 201 x 20 below 24C Solidification1 x 151 x 151 x 151 x 202 x 152 x 20 between 2
45、4 and 66C Solidification1 x 152 x 153 x 153 x 204 x 204 x 20 between 66 C and 100 C (Note 1) Notes:1.A higher steam pressure may be required. 2.For sample transport lines (i.e. for on-line process stream analysis), at least two DN15 tracers (or as shown in the above table, whichever provides the hig
46、her heat input) are required if the pour point of the product is above the minimum ambient temperature. For the above table, the parameters used are: -LP Steam 3.5 bar (ga), 150C; -50 mm mineral wool insulation for lines up to and including DN 100; -90 mm mineral wool insulation for lines DN 150 to
47、DN 600; -air temperature = minus 10 C; -wind velocity = 10 m/s. Tracers shall not be provided with branches. DEP 31.38.30.11-Gen. December 1997 Page 7 Each tracer shall have a valve just after the steam supply header and just before the condensate header. Tubing can be used for tracing of in-line eq
48、uipment such as strainers. Copper, carbon steel or stainless steel tubing may be used depending on the method of application. Tracers shall follow the contours of the piping to be heated from the highest point sloping towards the steam trap. Pockets should be avoided, and the maximum accumulated poc
49、ket depth is 3 m. Single and multiple tracers shall run along the underside of horizontal lines, or at either side of the supporting shoes. For details see (Appendix 2). Multiple tracers may be connected to a common steam supply line, but each shall have an individual steam trap and block valve. If systems are designed to discharge sub-cooled condensate (i.e. below saturated steam temperature), extra care shall be taken to ensure a constant slope of the tracer towards the steam trap, in order to avoid excessive water hammer effects. Multiple tracers on vertical pipes shall
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