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MSS SP- 64996

Standard Finishes forContact Faces of Pipe Flanges

and Connecting-End Flanges

of Valves and Fittings

Standard Practice

Developed and Approved by the

Manufacturers Standardization Society of the

Valve and Fittings Industry, Inc.

127 Park Street, NE

Vienna, Virginia 22180

(703) 281-6613

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MSS STANDARD PRACTICE SP-6

An MSS Standard Practice is intended as a basis for common practice by the manufacturer, the user, andthe general public. The existence of an MSS Standard Practice does not in itself preclude the manufacture,sale, or use of products not conforming to the Standard Practice. Mandatory conformance is established only

by reference in a code, specification, sales contract, or public law, as applicable.

Substantive changes in this 1996 edition are flagged by parallel bars as shown on the margins of thisparagraph. The specific detail of the change may be determined by comparing the material flagged with

that in the previous edition.

U.S. customary units in this SP are the standard; the metric units are for reference only.

Other standards documents referred to herein are identified by the date of issue that was applicable to thisstandard at the date of issue of this standard. See Annex A. This Standard shall remain silent on the applicability of

those other standards of prior or subsequent dates of issue even though provisions of concern may not havechanged. References contained herein which are bibliographic in nature are noted as supplemental in the text.

Anr! partqf this standardmav be quoted. Credit lines should read Extracted from MSS SP-6, 1996, Mithpermission of the publisher, the Manufacturers Standardization Society. Reproduction prohibited undercopj,right convention unless written permission is granted by the Manufacturers Standardization Societ?! qf the

Valve and Fittings Industry, Inc.

Originally Approved December, 1929

Copyright 0, 1985 byManufacturers Standardization Society

of theValve and Fittings Industry, Inc.

Printed in U.S.A.

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STANDARD FINISHES FOR CONTACT FACES

OF PIPE FLANGES AND CONNECTING END FLANGES

OF VALVES AND FITTINGS

1. SCOPE Ra Standards (See ASME B46.1) andnot by instruments having stylus tracers

1.1 This standard pertains to the finish ofgasket contact faces of pipe flanges and

end flanges of valves and fittings.

and electronic amplification. The finishesrequired are given in Table 1. Other finishes

may be furnished by agreement between

purchaser and manufacturer.

1.2 It is intended for application to products

for which ASME B16 Standards do notcontain complete facing finish require-ments or for which there are no such

Standards.

Other dimensions (in Table 1) are also

approximate and not subject to rejection

by depth gage measurement or precision

instrument measurements.

2. DEFINITIONS 3. LIMITATIONS

2.1 The term Ra (roughness average) is ex-pressed in micro-inches @in) [micro-metersb-WI.

3.1 Surface finishes listed are not necessarily

optimum for all gasket types of materials.

2.2 Flange Facing Finish. The finish of con-netting end flanges of valves and fittingsshall be judged by visual comparison with

3.2 On flat (plain) faces, serrations need not

extend beyond corresponding raised face

diameter.

FLAT l/16 RAISED l/4 RAISED RINGFACE FACE FACE JOINT

Ll SMALL MALE & LARGE MALE & SMALL TONGUE 81 LARGE TONGUE &FEMALE FEMALE GROOVE GROOVE

FIGURE 1 - TYPES OF CONTACT FACES FOR FLANGES

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TABLE 1. STANDARD FINISHES FOR CONTACT FACES OF PI PE FLANGES AND

CONNECTING-END FLANGES OF VALVES AND FITTINGS

Type ofContactFaces

Flat or l/16 (1.6mm) Raised Face

l/4 (6.4 mm)Raised - Large Male& Female

Small Male &Female, Large &Small Tongue &Groove

Ring Joint - SideWans of Groove

Steel

Serrated: spiral orconcentric, 45 to 55 perinch (25.4 mm) rec-ommended.The resultant surfacefinish shall have a 125to 250 pin. (3.2 to 6.3pm) Ra.

Serrated same as Flat

Sametb as FlatSmoot: 125 pin. (3.2urn) Ra max.Smooth: 63 pin. (1.6pm) Ra max.

Ductile Iron

SmoothCb: 250 pin (6.3 $moothb): 250 pin (6.3pm) Ra max., Lm) Ra max.,or or

Serrated: spiral orconcentric, 11 to 50 perin. (25.4 mm). Depthapprox. 0.003 to 0.020in. (0.075 to 0.5 10 mm)

serrated: spiral, 1 1 to50 per in. (25.4 mm) or:oncentric, 8 or more)er i n . (25.4 mm).Depth approx. 0.003 toI.020 in. (0.075 toI.5 10 mm)

Same as Flat

SameCh as Flat

Smooth: 63~ in. (1.6pm) Ra max.

Gray Iron Bronze

SmoothCb! 125 pin (3.2pm) Ra max.,or

Se r ra t ed : sp i ra l otconcentric, 30 to 80 perin. (25.4 mm). Depthapprox. 0.003 to 0.020in. (0.075 to 0.5 10 mm)

NOTES:

Unless otherwise ordered, the manufacturer can supply either spiral or concentric grooves for serrations. The spiralmachining operation is commonly accomplished with the cutting tool having 0.06 in. (1.6 mm) or larger tip radius.

hUnless otherwise ordered , the manufacturer may supply either the serrated or smooth finish.

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REFERENCED STANDARDS AND APPLICABLE DATES

This Annex is an integral part of this standard practice which is placed after the main text for convenience.

Standard Name or Designation

ASME, ANSI/ASME, ANSI, ASME/ANSIB46.1-1985 Surface Texture

The following organizations publish the above standard:

ANSI American National Standards Institute, Inc.11 West 42nd Street, New York, NY 10036

ASME The American Society of Mechanical Engineers345 East 47th Street, New York, NY 100 17-2392

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