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SEMI F3-94 © SEMI 1990, 2003 2 7.1.5 Surfaces for welding should be clean an d should be free from o xidation, disco loration, oi l, scale, chips , or other material that is detrimental to welding. 7.1.6 All components s…

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SEMI F3-94 © SEMI 1990, 2003 1
SEMI F3-94 (Withdrawn 1103)
GUIDE FOR WELDING STAINLESS STEEL TUBING FOR
SEMICONDUCTOR MANUFACTURING APPLICATIONS
NOTICE: This document was balloted and approved
for withdrawal in 2003.
1 Purpose
1.1 The purpose of this guide is to provide instructions
to increase the awareness of the user to the available
procedures for welding stainless steel gas distribution
systems, and to provide information from which
subsequent evaluations and standardization can be
derived.
2 Scope
2.1 This guide covers the general requirements for the
welding of stainless steel gas distribution systems.
3 Referenced Documents
NOTE: The following documents become part of the guide to
the extent that they are included herein.
3.1 The referenced documents are to be their current
edition as published by their sponsors.
3.2 SEMI Specification
SEMI F2 — Specification for 316L Stainless Steel
Tubing for General Purpose Semiconductor
Manufacturing Applications
3.3 ANSI/ASME Specifications
1
B16.25 — Butt Welding Ends
B31.3 — Chemical Plant and Petroleum Refining
Piping
Boiler and Pressure Vessel Code — Section IX,
Qualification Standard for Welding and Brazing
Procedures, Welders, Brazers, and Welding and
Brazing Operators
3.4 AWS Specification
2
AWS D10.9 — Specification and Qualification of
Welding Procedures and Welders for Piping and
Tubing
3.5 ASTM Specification
3
1 American Society of Mechanical Engineers, 345 East 47th Street,
New York, NY 10017
2 American Welding Society, 550 NW LeJeune Road, P.O. Box
351040, Miami, Florida 33135
A450 (Section 25) — General Requirements for
Carbon, Ferritic Alloy, and Austenitic Steel Tubes
4 General Requirements
4.1 All welding performed under this guide should
conform to the applicable requirements of the ASME
Boiler and Pressure Vessel Code, Section IX, ANSI
B16.25, B31.3 Chapter V, and AWS D10.9, to the
extent that they are included herein.
5 Materials
5.1 All materials to be welded should be manufactured
to ASTM specifications and so certified by the
manufacturer. Certification should conform to ASTM
A-450, Section 25.
5.2 All seamless austenitic stainless steel tubing should
be in conformance with SEMI F2.
6 Testing of Welders
6.1 All welds should be based upon Welding Procedure
Specifications and be documented with associated
Procedure Qualification Records in accordance with
ASME Boiler and Pressure Vessel Code, Section IX, or
with AWS D10.9.
6.2 Qualification of the welding procedures to be used,
and of the performance of welders and welding
operators, should conform to the requirements of the
ASME Boiler and Pressure Vessel Code, Section IX,
Articles II and III, or AWS D10.9.
7 Welding Procedure
7.1 Component Preparation
7.1.1 All weld end preparation should be done in such
a manner as to minimize the introduction of
contaminants into the system.
7.1.2 All cutting of component or tubing weld ends
should be done with a sharp-edged tool. No lubricants
of any kind should be allowed.
7.1.3 All component and tubing weld ends that are to
be cut should be de-burred without chamfering.
7.1.4 All welding ends requiring preparation for
procedures requiring the use of filler material should be
prepared in accordance with ANSI/ASME B16.25.
3 American Society for Testing and Materials, 100 Barr Harbor
Drive, West Conshohoken, PA 19428-2959
SEMI F3-94 © SEMI 1990, 2003 2
7.1.5 Surfaces for welding should be clean and should
be free from oxidation, discoloration, oil, scale, chips,
or other material that is detrimental to welding.
7.1.6 All components should be maintained in a clean
condition until welded into the system.
7.2 Welding Requirements
7.2.1 Welding equipment used to make welds should
be operated in accordance with the manufacturer’s
operating and safety instructions.
7.3 Welding Procedures
7.3.1 Prior to the welding of a particular size, wall
thickness, alloy, and heat of material, sample welds
should be made, dissected, and analyzed.
7.3.2 These welds should be checked for poor
penetration, joint contamination, joint soundness,
surface oxidation, discoloration, pitting, cracking,
defects of fit-up, or defects of workmanship.
7.3.3 Once a sample weld is found to be acceptable, the
sample weld should be the on-site work sample against
which other welds of the same size, wall thickness,
alloy, and heat of material are judged. All essential and
supplementary essential variables should be
documented in the procedure qualification record.
7.3.4 Any significant deviation(s) from the on-site
work sample (7.3.3) will cause the weld(s) to be
rejected. Rejected welds should be removed and
replaced.
7.3.5 Sample test welds should be made periodically.
These tests should be compared to the on-site work
sample (7.3.3). Deviation from the on-site work sample
should be cause for rejection. The sample test welds
should be made at/when:
1. The beginning of each shift.
2. The end of each shift.
3. Any change in welding procedure, materials, tubing
size, equipment, or equipment adjustments are
made.
4. Any time that a concern or deviation to the weld
quality has occurred.
7.3.6 Sample test welds should be kept on file and may
be reviewed at any time during the construction.
7.3.7 Where a weld is found defective, the preceding
two welds should be tested as indicated in Paragraph
7.3.2. If either of these welds shows signs of poor
penetration, joint contamination, lack of joint
soundness, surface oxidation, discoloration, pitting,
cracking, defects of fit-up, or defects of workmanship,
then all welds made since the last welding procedure
was established should be removed and replaced.
7.4 Weld Set-up
7.4.1 Check parameters and verify that they are in
accordance with the qualified welding procedure.
7.5 Purging
7.5.1 During welding, all tubes, fittings, valves, sub-
assemblies, and all other components should be
continuously purged.
7.5.2 Automatic orbital head welding equipment
should supply a constant gas-backing shield to the weld
head during welding.
7.5.3 During all welding, a sufficient amount of
purge/shield gas should be maintained until the weld
head is removed from the newly welded parts.
7.5.4 Both purge/shield gas supply lines should contain
flow indicators to ensure proper purging.
7.6 Weld Identification
7.6.1 A daily log should be maintained on all welds,
and as-built drawings recording all data should be
maintained in the welding area.
7.6.2 All welds should be identified with a code
number and cross-referenced with the drawings for
future evaluation.
7.7 Additional Requirements
7.7.1 Maintain sufficient distance between weld joints
and valve seats to avoid damage to valve seats or valve
stem tips.
SEMI F3-94 © SEMI 1990, 2003 3
NOTICE: These standards do not purport to address
safety issues, if any, associated with their use. It is the
responsibility of the user of these standards to establish
appropriate safety and health practices and determine
the applicability of regulatory limitations prior to use.
SEMI makes no warranties or representations as to the
suitability of the standards set forth herein for any
particular application. The determination of the
suitability of the standard is solely the responsibility of
the user. Users are cautioned to refer to manufacturer’s
instructions, product labels, product data sheets, and
other relevant literature respecting any materials
mentioned herein. These standards are subject to
change without notice.
The user’s attention is called to the possibility that
compliance with this standard may require use of
copyrighted material or of an invention covered by
patent rights. By publication of this standard, SEMI
takes no position respecting the validity of any patent
rights or copyrights asserted in connection with any
item mentioned in this standard. Users of this standard
are expressly advised that determination of any such
patent rights or copyrights, and the risk of infringement
of such rights, are entirely their own responsibility.