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[edit] Mechanical Seal Specification

This is a collaborative effort to develop an overlay for "Pumps - Shaft Sealing Systems for Centrifugal and Rotary Pumps", ANSI/API Standard 682, 3rd Edition, September 2004. (API 682 is functionally equivalent to the international standard ISO 21049.)

An overlay is defined as a document containing specific choices, comments, exceptions and additional requirements that are used to supplement an existing standard. The overlay takes precedence over the standard.

Many large companies have their own proprietary overlays to international standards. By participating in this wiki, rotating equipment engineers and technicians will be able to take part in developing a collaborative overlay that can be referenced and used to improve the standard. Some companies, especially smaller ones, may choose to use this overlay directly rather than develop their own overlay. Members of the API 682 and ISO 21049 committees can refer to this wiki overlay for the degree of worldwide acceptance and interpretation of the standard.

Format of Overlay

Paragraphs must be numbered in strict accordance to API 682, 3rd edition. This is absolutely necessary for readability and cross referencing. Existing paragraphs contained in API 682 should not be listed or quoted. It is not necessary to list every paragraph number; list only the paragraph numbers that are to be changed, clarified, commented upon, etc.

Paragraph numbers in API 682 are five levels deep; for example, Paragraph 10.3.1.2.8 is about testing. To add a new paragraph, use the sixth level, but preceded by "N". For example, an additional overlay paragraph inserted between existing 10.3.1.2.8 and 10.3.1.2.9 would be numbered 10.3.1.2.8.N1. If less than five levels are used, fill in the unused levels with zero (0) and add .N1 as the sixth level. There should be a minimum of new paragraphs added. Also, keep in mind that paragraphs added to this overlay would be fitted into the five level organization plan if adopted by the official standard.

Since API 682 reserves the word NOTE as a lead-in to paragraphs containing additional, informative, information, this overlay will use the word COMMENT for explanatory paragraphs.

1. Scope

1.0.0.0.0.N1 All specifications in this overlay are in addition to those of API 682 unless specifically noted as exceptions.

2. Normative references

3. Terms and definitions

4. Sealing systems

5. General

6. Design requirements

6.1.2.17 Table 1: Gas Barrier Outlet (GBO) connection should not be supplied for the 3NC configuration unless it is actually used.

COMMENT: Non-contacting Arrangement 3 seals use only Gas Barrier In (GBI), there is no Gas Barrier Out flow. The preference is to avoid an unused connection which must be plugged.

7. Specific seal configurations

8. Accessories

8.5.3.1.2 Seal flush coolers shall be designed for a minimum cooling water pressure of 150 psig.

9. Instrumentation

10. Inspection, testing and preparation for shipment

10.3.1.3 COMMENT: Table 8 has typographical errors. The base point temperature for mineral oil testing (column 4, row 6) should be 260 C (500 F); cyclic range (column 5, row 6) should be 150 C to 260 C (300 F to 500 F).

11. Data transfer

Annex A: Recommended seal selection procedure

Annex B: Typical materials standards for seal chamber and mechanical seal components

Annex C: Mechanical seal data sheets

Annex D: Mechanical seal codes

Annex E: Seal and pump vendor interface responsibilities

Annex F: Heat generation and heat soak calculations

Annex G: Standard flush plans and auxiliary hardware

Annex H: Inspector checklist for all seals

Annex I: Form for mechanical seal qualification test

Annex J: Mechanical seals data requirements form

Bibliography