Pumps—Shaft Sealing Systems for Centrifugal and Rotary Pumps

ANSI/API Standard 682

Third Edition, September 2004

ISO 21049: 2004, (Identical) Pumps—Shaft Sealing Systems for Centrifugal and Rotary Pumps

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Copyright © 2004 American Petroleum Institute

API Foreword

API publications may be used by anyone desiring to do so. Every effort has been made by the Institute to assure the accuracy and reliability of the data contained in them; however, the Institute makes no representation, warranty, or guarantee in connection with this publication and hereby expressly disclaims any liability or responsibility for loss or damage resulting from its use or for the violation of any federal, state, or municipal regulation with which this publication may conflict.

Suggested revisions are invited and should be submitted to API, Standards department, 1220 L Street, NW, Washington, DC 20005, standards@api.org.

This American National Standard is under the jurisdiction of the API Committee on Refinery Equipment, Subcommittee on Mechanical Equipment. This standard is considered identical to the English version of ISO 21049. ISO 21049 was prepared by Technical Committee ISO/TC 115, Pumps, SC 3, Installation and special applications, in collaboration with Technical Committee, ISO TC 67, Materials, equipment, and offshore structures for petroleum, petrochemical and natural gas industries, SC 6 Procession equipment and systems.

Contents

Page

API Foreword ii

Foreword vi

Introduction vii

1. Scope 1

2. Normative references 1

3. Terms and definitions 3

4. Sealing systems 10

   1. Seal categories, types and arrangements 10

      1. General 10

      2. Seal categories 10

      3. Seal types 11

      4. Seal arrangements 11

      5. Seal orientations 12

   2. Objectives 12

   3. Specifying and/or purchasing a sealing system 12

5. General 19

   1. Unit responsibility 19

   2. Dimensions 20

6. Design requirements 20

   1. Common design requirements (all categories) 20

      1. General information 20

      2. Seal chamber and gland plate 23

      3. Cartridge seal sleeves 30

      4. Mating rings 32

      5. Flexible elements 34

      6. Materials 34

   2. Design requirements (category-specific) 38

      1. Category 1 seals 38

      2. Category 2 seals 39

      3. Category 3 seals 40

7. Specific seal configurations 41

   1. Arrangement 1 seals 41

      1. Seal sleeves 41

      2. Seal chamber and gland plate 41

   2. Arrangement 2 seals 41

      1. General 41

      2. Seal sleeves 42

      3. Seal chamber and gland plates 42

      4. Contacting wet seals with a liquid buffer fluid (2CW-CW) 43

      5. Seal chamber and gland plates for contacting wet inner seal with a dry-running

         containment seal (2CW-CS) 43

      6. Seal chamber and gland plates for non-contacting inner seal with a dry-running

         containment seal (2NC-CS) 44

   3. Arrangement 3 seals 44

      1. General 44

      2. Seal sleeves 45

      3. Seal chamber and gland plates 45

      4. Contacting wet seal configurations with a liquid barrier fluid (3CW-FB, 3CW-FF, 3CW-BB) 45

7.3.5 Standard seal types and arrangements for non-contacting seal configurations with a gas barrier fluid (3NC-FB, 3NC-FF, 3NC-BB) 46

1. Accessories 46

   1. Auxiliary piping systems 46

   2. Mechanical seal flush/cooling systems (Group I) 49

   3. Quench systems (Group II) 50

   4. Cooling-water systems (Group III) 50

   5. Accessories and auxiliary system components 51

      1. Cyclone separator 51

      2. Flow control orifice 52

      3. Seal flush coolers 53

      4. Barrier/buffer fluid reservoirs 53

      5. Barrier/buffer-fluid selection criteria 57

   6. Barrier/buffer fluid and seal flush positive-circulating devices 57

      1. General 57

      2. Internal circulating device 57

      3. External circulating pump 57

      4. External seal flush systems 57

      5. Condensate collection reservoir 58

      6. Barrier/buffer-gas supply systems 58

2. Instrumentation 59

   1. General 59

   2. Temperature-indicating gauges 59

   3. Thermowells 59

   4. Pressure gauges 59

   5. Switches 60

      1. Alarm, trip and control switches 60

      2. Pressure switches 60

      3. Level switches 61

      4. Flow switches 61

   6. Level indicators 61

   7. Flow instruments 61

      1. Flow indicators 61

      2. Flow meters 61

      3. Flow transmitters 61

   8. Relief valves 61

   9. Regulators 62

   10. Pressure amplifiers 62

3. Inspection, testing and preparation for shipment 62

   1. General 62

   2. Inspection 62

   3. Testing 63

      1. Seal qualification testing 64

      2. Hydrostatic test for pressure-containing mechanical seal parts and accessories 77

      3. Test of job seal by seal manufacturer 78

      4. Air test 78

      5. Test of job seal by pump manufacturer 78

   4. Preparation for shipment 79

4. Data transfer 79

   1. General 79

   2. Proposal data 80

   3. Contract data 81

Annex A (informative) Recommended seal selection procedure 85

Annex B (informative) Typical materials standards for seal chamber and mechanical seal

components 130

Annex C (normative) Mechanical seal data sheets 137

Annex D (informative) Mechanical seal codes 146

Annex E (normative) Seal and pump vendor interface responsibilities 148

Annex F (informative) Heat generation and heat soak calculations 150

Annex G (normative) Standard flush plans and auxiliary hardware 157

Annex H (informative) Inspector checklist for all seals 188

Annex I (normative) Form for mechanical seal qualification test 189

Annex J (normative) Mechanical seals data requirements form 192

Bibliography 193

Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights.

ISO 21049 was prepared by Technical Committee ISO/TC 115, Pumps, Subcommittee SC 3, Installation and special applications, in collaboration with Technical Committee ISO/TC 67, Materials, equipment and offshore structures for petroleum, petrochemical and natural gas industries, SC 6, Processing equipment and systems.

Introduction

This International Standard is based on the accumulated knowledge and experience of manufacturers and users of equipment in the petroleum, natural gas and chemical industries, but its use is not restricted to these industries.

Users of this International Standard should be aware that further or differing requirements may be needed for individual applications. This International Standard is not intended to inhibit a vendor from offering, or the purchaser from accepting, alternative equipment or engineering solutions for the individual application. This may be particularly appropriate where there is innovative or developing technology. Where an alternative is offered, the vendor should identify any variations from this International Standard and provide details.

The purpose of this International Standard is to assist purchasers with the selection and operation of mechanical seals for pumps.

This International Standard is a stand-alone seal standard and is referenced normatively in ISO 13709. It is applicable to both new and retrofitted pumps, and to pumps other than ISO 13709 pumps (e.g. ASME B73.1, ASME B73.2 and API 676 pumps).

In this International Standard, where practical, US Customary units are included in brackets for information.

A bullet () at the beginning of a clause or subclause indicates that either a decision is required or further information is to be provided by the purchaser. This information should be indicated on data sheets or stated in the enquiry or purchase order (see examples in Annex C).

Pumps — Shaft sealing systems for centrifugal and rotary pumps

1. Scope

   
   

   This International Standard specifies requirements and gives recommendations for sealing systems for centrifugal and rotary pumps used in the petroleum, natural gas and chemical industries. It is applicable mainly for hazardous, flammable and/or toxic services where a greater degree of reliability is required for the improvement of equipment availability and the reduction of both emissions to the atmosphere and life-cycle sealing costs. It covers seals for pump shaft diameters from 20 mm (0,75 in) to 110 mm (4,3 in).

   
   

   This International Standard is also applicable to seal spare parts and can be referred to for the upgrading of existing equipment. A classification system for the seal configurations covered by this International Standard into categories, types, arrangements and orientations is provided.

   
   

2. Normative references

The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 7 (all parts), Pipe threads where pressure-tight joints are made on the threads

ISO 261, ISO general-purpose metric screw threads — General plan

ISO 262, ISO general-purpose metric screw threads — Selected sizes for screws, bolts, and nuts

ISO 286-2, ISO system of limits and fits — Part 2: Tables of standard tolerance grades and limit deviations for holes and shafts

ISO 724, ISO general-purpose metric screw threads — Basic dimensions

ISO 965 (all parts), ISO general-purpose metric screw threads — Tolerances

ISO 3069, End-suction centrifugal pumps — Dimensions of cavities for mechanical seals and for soft packing

ISO 4200, Plain end steel tubes, welded and seamless — General tables of dimensions and masses per unit length

ISO 7005-1, Metallic flanges — Part 1: Steel flanges

ISO 10438 (all parts), Petroleum, petrochemical and natural gas industries — Lubrication, haft-sealing and control-oil systems and auxiliaries

ISO 13709, Centrifugal pumps for petroleum, petrochemical and natural gas industries

ISO 15649, Petroleum and natural gas industries — Piping

IEC 60079 (all parts), Electrical apparatus for explosive gas atmospheres

IEC 60529, Degrees of protection provided by enclosures (IP code)