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Recommended Practice

ISA-RP42.1-1992Approved September 30, 1991

Nomenclature for

Instrument Tube Fittings

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Copyright 1992 by the Instrument Society of America. All rights reserved. Printed in the UnitedStates of America. No part of this publication may be reproduced, stored in a retrieval system, ortransmitted in any form or by any means (electronic, mechanical, photocopying, recording, orotherwise), without the prior written permission of the publisher.

ISA67 Alexander DriveP.O. Box 12277Research Triangle Park, North Carolina 27709

ISA-RP42.1 Nomenclature for Instrument Tube Fittings

ISBN 1-55617-256-7

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ISA-RP42.1-1992 3

Preface

This preface is included for informational purposes and is not part of ISA-RP42-1.

This recommended practice has been prepared as part of the service of ISA toward a goal ofuniformity in the field of instrumentation. To be of real value, this document should not be static,but should be subject to periodic review. Toward this end, the Society welcomes all commentsand criticisms, and asks that they be addressed to the Secretary, Standards and PracticesBoard, ISA, 67 Alexander Drive, P.O. Box 12277, Research Triangle Park, NC 27709, Telephone(919) 549-8411, e-mail: standards@isa.org.

The ISA Standards and Practices Department is aware of the growing need for attention to themetric system of units in general, and the International System of Units (SI) in particular, in thepreparation of instrumentation standards. The Department is further aware of the benefits toU.S.A. users of ISA standards of incorporating suitable references to the SI (and the metricsystem) in their business and professional dealings with other countries. Toward this end, this

Department will endeavor to introduce SI-acceptable metric units in all new and revisedstandards to the greatest extent possible. The Metric Practice Guide, which has been publishedby the Institute of Electrical and Electronics Engineers as ANSI/IEEE Std. 268-1982, and futurerevisions, will be the reference guide for definitions, symbols, abbreviations, and conversionfactors.

It is the policy of ISA to encourage and welcome the participation of all concerned individuals andinterests in the development of ISA standards. Participation in the ISA standards-makingprocess by an individual in no way constitutes endorsement by the employers of the individual, ofthe ISA, or of any of the standards that ISA develops.

The following people served as members of ISA Committee RP42:

NAME COMPANY

W. D. Wilson Crawford Fitting Company

F. Zikas Parker Hannifin Corporation

K. L. Hopkins BP America

B. J. Traylor Sandwell, Inc.

B. Fogleman Fogleman Company

R. Lacluyse Lesman Instrument Company

This recommended practice was approved for publication by the ISA Standards and PracticesBoard on September 30, 1991.

NAME COMPANY

J. Rennie Factory Mutual Research Corporation

W. C. Weidman Gilbert/Commonwealth, Inc.

H. D. Bauman H. D. Bauman & Associates

D. N. Bishop Chevron USA. Inc.

C. R. Gross Dow Chemical

H. S. Hopkins Utility Products of Arizona

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4 ISA-RP42.1-1992

K. P. Lindner Endress & Hauser GmbH & Company

G. R. McFarland ABB Power Automation, Inc.

E. M. Nesvig ERDCO Engineering Corporation

R. D. Prescott Moore Products Company

D. E. Rapley Rapley Engineering Services

R. H. Reimer Allen-Bradley Company

R. C. Webb Pacific Gas & Electric CompanyDr. J. R. Whetstone Nat'l Inst. of Standards & Technology

M. A. Widmeyer The Supply Company

C. A. Williams Eastman Kodak Company

P. Bliss* Consultant

W. Calder III* The Foxboro Company

L. N. Combs* Consultant

N. Conger* Retired

T. J. Harrison* Florida State University

R. T. Jones* Retired

R. E. Keller* Consultant

E. C. Magison* Honeywell,Inc.

R. G. Marvin* Consultant

A. P McCauley* Chagrin Valley Controls,Inc.

W. B. Miller* Retired

J. W. Mock* Bechtel Western Power Corporation

G. Platt* Consultant

K. Whitman* ABB Combustion Engineering

J. R. Williams* Stearns Catalytic Corporation

*Directors Emeriti

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ISA-RP42.1-1992 5

Contents

1 Purpose ............................................................................................................................. 7

2 Scope ................................................................................................................................ 7

3 Specifications ................................................................................................................... 7

4 Fittings .............................................................................................................................. 9

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ISA-RP42.1-1992 7

1 Purpose

The purpose of this standard is to aid in the proper specification and application of instrumenttube fittings by standardizing nomenclature. Proper use of this standard should result in data

that: more accurately describes a particular fitting for all interested parties; permits bettercommunications between manufacturer, vendor, purchaser, and ultimate user; providesstandardized nomenclature to be used by drafting, billing, purchasing, and stores groups; andmakes more clear the use of standardized drafting symbols and abbreviations for the morecommonly used instrument tube fittings.

2 Scope

This standard defines nomenclature for tube fittings most commonly used in instrumentation. Itis not intended as a substitute for manufacturers' catalog numbers, nor does it apply to specialfittings. This standard is intended to apply to mechanical flared and flareless tube fittings ascommonly used in instrument tubing systems.

3 Specifications

3.1 Each tube fitting in a bill of material or purchase order should be specified in the following order:

a) Fitting material

b) Tube outside diameter

c) Pipe thread (NPT* or NPTF**)

d) Standard name(see Section 4)

e) Flared or flareless

Example: brass 1/4 in. x 1/4 in. NPT male connector, flareless

3.2 Special tube fittings not covered by this standard should be specified as listed in manufacturers'

catalogs. Manufacturer and catalog number should be given after size and other pertinent data.

3.3 The ports for each tube tee or cross shown in details 4.8 to 4.13 should be specified in theorder indicated by the port numbers in the detailed drawings.

Example: Using 4.9: brass 1/4 in. x 1/4 in. NPT x 1/4 in. tube male run tee, flareless

*ANSI Standard Taper Pipe Thread from ANSI B2.1-1968

**ANSI Standard Taper Pipe Thread (Dryseal) from ANSI B1.20.3

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8 ISA-RP42.1-1992

3.4 Standard abbreviations may be used on drawings and bills of material as shown in Section 4.

3.5 Symbols used on drawings should be as shown in Section 4.

3.6 When metric tubing sizes are in use, the specifications should use metric dimensions. If pipethreads other than NPT and NPTF are required, they should be spelled out as follows:

Example: Brass 6 mm OD x 1/4 in. ISO R7 tapered male connector, flared

Male or female ISA taper (ISO R7)

Male or female ISO parallel (ISO R228)

3.7 CAD-generated detailed drawings may be substituted for the equivalent schematic symbol.

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ISA-RP42.1-1992 9

4 Fittings

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10 ISA-RP42.1-1992

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12 ISA-RP42.1-1992

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Developing and promulgating technically sound consensus standards,

recommended practices, and technical reports is one of ISA's primarygoals. To achieve this goal the Standards and Practices Departmentrelies on the technical expertise and efforts of volunteer committeemembers, chairmen, and reviewers.

ISA is an American National Standards Institute (ANSI) accreditedorganization. ISA administers United States Technical AdvisoryGroups (USTAGs) and provides secretariat support for InternationalElectrotechnical Commission (IEC) and International Organization forStandardization (ISO) committees that develop process measurementand control standards. To obtain additional information on theSociety's standards program, please write:

ISAAttn: Standards Department67 Alexander DriveP.O. Box 12277Research Triangle Park, NC 27709

ISBN: 1-55617-256-7