TECHNICAL SPECIFICATION

COATING REQUIREMENTS FOR BOLTS AND NUTS

(AMENDMENTS/SUPPLEMENTS TO ASTM B 841)

MESC SPE 81/007

February 2017

MESC SPECIFICATION DOCUMENT

This document is restricted. Neither the whole nor any part of this document may be disclosed to any third party without the prior written consent of Shell Global
Solutions International B.V., The Netherlands. The copyright of this document is vested in this company. All rights reserved. Neither the whole nor any part of this
document may be reproduced, stored in any retrieval system or transmitted in any form or by any means (electronic, mechanical, reprographic, recording or otherwise)
without the prior written consent of the copyright owner.
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PREFACE

MESC (Materials and Equipment Standards and Code) SPE documents reflect the views, at the time of publication, of:
Shell Global Solutions International B.V. (Shell GSI)
and/or
Shell International Exploration and Production B.V. (SIEP)
and/or
other Shell Service Companies.
They are based on the experience acquired during their involvement with the design, construction, operation and
maintenance of processing units and facilities, and they are supplemented with the experience of Shell Operating Units.
Where appropriate they are based on, or reference is made to, international, regional, national and industry standards.
The objective is to set the recommended standard for good design and engineering practice applied by Shell companies
operating an oil refinery, gas handling installation, chemical plant, oil and gas production facility, or any other such
facility, and thereby to achieve maximum technical and economic benefit from standardization.
The information set forth in these publications is provided to Shell companies for their consideration and decision to
implement. This is of particular importance where MESC SPEs may not cover every requirement or diversity of condition
at each locality. The system of MESC SPEs is expected to be sufficiently flexible to allow individual Operating Units to
adapt the information set forth in MESC SPEs to their own environment and requirements.
When Contractors or Manufacturers/Suppliers use MESC SPEs they shall be solely responsible for the quality of work
and the attainment of the required design and engineering standards. In particular, for those requirements not
specifically covered, the Principal will expect them to follow those practices, which will achieve the same level of
integrity as reflected in the MESC SPEs. If in doubt, the Contractor or Manufacturer/Supplier shall, without detracting
from his own responsibility, consult the Principal or its technical advisor.
The right to use MESC SPEs is granted by Shell GSI, in most cases under Service Agreements primarily with Shell
companies and other companies receiving technical advice and services from Shell GSI or another Shell Service
Company. Consequently, three categories of users of MESC SPEs can be distinguished:
1) Operating Units having a Service Agreement with Shell GSI or other Shell Service Company. The use of MESC
SPEs by these Operating Units is subject in all respects to the terms and conditions of the relevant Service
Agreement.
2) Other parties who are authorized to use MESC SPEs subject to appropriate contractual arrangements (whether
as part of a Service Agreement or otherwise).
3) Contractors/subcontractors and Manufacturers/Suppliers under a contract with users referred to under 1) or 2)
which requires that tenders for projects, materials supplied or - generally - work performed on behalf of the said
users comply with the relevant standards.
Subject to any particular terms and conditions as may be set forth in specific agreements with users, Shell GSI
disclaims any liability of whatsoever nature for any damage (including injury or death) suffered by any company or
person whomsoever as a result of or in connection with the use, application or implementation of any MESC SPE,
combination of MESC SPEs or any part thereof, even if it is wholly or partly caused by negligence on the part of Shell
GSI or other Shell Service Company. The benefit of this disclaimer shall inure in all respects to Shell GSI and/or any
Shell Service Company, or companies affiliated to these companies, that may issue MESC SPEs or require the use of
MESC SPEs.
Without prejudice to any specific terms in respect of confidentiality under relevant contractual arrangements, MESC
SPEs shall not, without the prior written consent of Shell GSI, be disclosed by users to any company or person
whomsoever and the MESC SPEs shall be used exclusively for the purpose for which they have been provided to the
user. They shall be returned after use, including any copies, which shall only be made by users with the express prior
written consent of Shell GSI. The copyright of MESC SPEs vests in Shell GSI. Users shall arrange for MESC SPEs to
be held in safe custody and Shell GSI may at any time require information satisfactory to them in order to ascertain how
users implement this requirement.
All administrative queries should be directed to the MESC SPE Administrator in Shell GSI.
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TABLE OF CONTENTS
PART I INTRODUCTION ........................................................................................................ 4
1.1 SCOPE........................................................................................................................ 4
1.2 DISTRIBUTION, INTENDED USE AND REGULATORY CONSIDERATIONS ......... 4
1.3 DEFINITIONS ............................................................................................................. 4
1.4 CHANGES SINCE PREVIOUS EDITION ................................................................... 5
1.5 COMMENTS ON THIS MESC SPE ............................................................................ 5
PART II AMENDMENTS/SUPPLEMENTS TO ASTM B 841 – 99 (R 2010) ............................ 6
PART III REQUIREMENTS FOR FLUOROPLASTIC (PTFE) COATING: ................................ 8
PART IV REFERENCES ......................................................................................................... 11
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PART I INTRODUCTION

1.1 SCOPE
This MESC SPE specifies the requirements and procedures for the coating systems to be
applied on bolts and nuts for the purpose of corrosion protection of the bolt and nuts. All
coating systems to be used shall be applied and tested according the guidelines given in
this specification.
This MESC SPE shall apply in addition to the applicable MESC Buying Description,
purchase order or requisition sheet.
Part II of this MESC SPE is written as amendments and supplements to ASTM B 841 – 99
(R 2010). The clause numbering of ASTM B 841 – 99 (R 2010) has been retained and any
amendments are identified as ‘Add’, ‘Modify to read’ or ‘Delete’. Any clauses of ASTM B
841 – 99 (R 2010) that are not amended or supplemented by this MESC SPE shall apply as
written.
Part III of this MESC SPE specifies the requirement and procedure for fluorroplastic (PTFE)
coating.

1.2 DISTRIBUTION, INTENDED USE AND REGULATORY CONSIDERATIONS

Unless otherwise authorised by Shell GSI, the distribution of this MESC SPE is confined to
Shell companies and, where necessary, to Contractors and Manufacturers/Suppliers
nominated by them..
This MESC SPE is intended for use in oil refineries, chemical plants, gas plants, exploration
and production facilities and, where applicable, supply/distribution installations.
If national and/or local regulations exist in which some of the requirements may be more
stringent than in this MESC SPE the Contractor shall determine by careful scrutiny which of
the requirements are the more stringent and which combination of requirements will be
acceptable with regard to safety, environmental, economic and legal aspects. In all cases
the Contractor shall inform the Principal of any deviation from the requirements of this
MESC SPE which is considered to be necessary in order to comply with national and/or
local regulations. The Principal may then negotiate with the Authorities concerned, the
objective being to obtain agreement to follow this MESC SPE as closely as possible.

1.3 DEFINITIONS
The Contractor is the party that carries out all or part of the design, engineering,
procurement, construction, commissioning or management of a project, or operation or
maintenance of a facility. The Principal may undertake all or part of the duties of the
Contractor.
The Manufacturer/Supplier is the party that manufactures or supplies equipment and
services to perform the duties specified by the Contractor.
The Principal is the party that initiates the project and ultimately pays for its design and
construction. The Principal will generally specify the technical requirements. The Principal
may also include an agent or consultant authorised to act for, and on behalf of, the
Principal.
The word shall indicates a requirement.
The word should indicates a recommendation.
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1.4 CHANGES SINCE PREVIOUS EDITION

The previous edition of this MESC SPE was dated February 2016. The change is to
remove reference to the Global Surface Network.

1.5 COMMENTS ON THIS MESC SPE

Comments on this MESC SPE may be sent to the MESC SPE Administrator at
MESC@shell.com.
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PART II AMENDMENTS/SUPPLEMENTS TO ASTM B 841 – 99 (R 2010)

4.2 Modify Chromate conversion coating for stud bolts and nuts shall be Type B and Type E.
to
The organic top coat type E shall comply with the specification contained in Part
read’
III.
4.3 Modify The coating thickness shall be 10 to 12 microns on parts with external threads.
to read’
The coating thickness shall be 15 to 18 microns on parts without threads.
Due to the thickness of coating required it might be necessary, for threaded parts
with tight tolerances, to provide additional thread clearance. The additional thread
clearance shall be in accordance with the relevant part of ISO 4024.The coating
thickness shall be 10 to 12 micron. The coating shall have finish type B (yellow
iridescent conversion).
6.4.1 Modify The thickness of coating everywhere on the significant surfaces as defined 3.2.1
to shall confirm to the requirements as specified in 4.3. Thread surfaces are not
read’ exempt from minimum thickness requirements.
The dimensional tolerance of most threaded articles, such as nuts, bolts, screws,
and similar fasteners with complementary threads, normally does not permit the
application of a coating thickness much greater than 8.0 μm. If heavier coatings are
required, allowance for the deposit buildup must be made during the manufacture
of the threaded articles.
6.9 Add Materials, other than stainless steels, which the producer considers to be passive
to the process, shall be activated with a nickel strike or other alternative process.
The producer is required to indicate on the Certified Test Report which surface
activation process(es), including nickel strike, have been performed.
7.1 Modify The purchaser and producer are urged to employ statistical process control in the
to coating process. Properly performed, statistical process control will assure coated
read’ products of satisfactory quality and will assure the amount of acceptance
inspection. The sampling plan used for the inspection of the quality coated article
shall be ASTM F 1470-09.
7.4 Add’ When a collection of coated articles (inspection lot, see 7.2) is examined for
compliance with the requirements placed on the articles, a relatively small number
of the articles (sample) is selected at random and is inspected. The inspection lot is
then classified as complying with the requirements based on the results of the
inspection of the sample. The size of the sample and the criteria for compliance are
determined by the application of statistics. The procedure is known as sampling
inspection. Guide ASTM F 1470-09 contain sampling plans that are designed for
sampling inspection of coatings.
8.7 Add’ Guide ASTM F 1470-09 shall be used for fasteners such as internally threaded,
externally threaded, and nonthreaded fasteners and washers. This guide provides
for two plans: one designated the “detection process” and one designated the
“prevention process.” The plan to be used shall be the “detection process” for at
least the following characteristics:
 Adhesion (coating) – Sample Level C
 Hydrogen embrittlement (where applicable,see 6.7 & 6.8) - Sample Level B
 Plating/coating thickness (weight) – Sample Level A
 Salt spray – Sample Level B
 Surface discontinuities – Sample Level B
 Surface roughness – Sample Level B
9.2 Add The producer or supplier shall be responsible for the performance of all inspection
requirements as specified herein. Except as otherwise specified in the contract or
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order. The purchaser retains the right to perform any of the inspection and tests
sets forth in this specification where such inspection and tests are deemed
necessary to ensure that supplies and services confirm to the prescribed
requirements.
10.1 Modify The producer or supplier shall provide certification in accordance with ISO 10474
to type 3.1. or EN 10204 type 3.1 that the finish was produced and tested in
read’ accordance with this specification and found to meet the requirements. A report of
the test results shall be furnished.
10.2 Add’ The test report shall include the following information:
 A reference to this specification.
 A reference to test method(s) used
 The location(s) of the test area(s) on each specimen
 The quantity of specimen tested
 The name of the operator and testing laboratory
 The date(s) on which the test(s) were performed.
 Any circumstances or conditions thought likely to affect the results or their
validity
 Any deviation from the test method specified
 The quantified results of the test(s)
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PART III REQUIREMENTS FOR FLUOROPLASTIC (PTFE) COATING:

3.0 PTFE Coating Materials:

The top coat for bolting components shall be Xylan 1070® (or) equivalent. The selected
material shall contain polytetrafluorethylene together with polyamide /polyimide ester and
colouring pigment and shall be the base cure type. The selected material shall withstand
the temperature range of -50°C to + 200 °C.
3.1 Thickness of coating:
The dry film thickness of the PTFE coating on the bolting component shall not be less than
25 microns and not greater than 40 microns. The coating shall be applied in accordance
with ASTM D823.
The application of coating shall be applied with a minimum of two (or) more layers.
3.2 Inspection and Testing:
3.2.1 Sampling Lot:
Guide ASTM F 1470-09 shall be used for fasteners such as internally threaded, externally
threaded, and nonthreaded fasteners and washers. This guide provides for two plans: one
designated the “detection process” and one designated the “prevention process.” The plan
to be used shall be the “detection process” for at least the following characteristics:
 Visual examination –Sample level B
 Thickness testing – Sample level A
 Hardness testing – Sample level B
 Solvent testing – Sample level C
 Adhesion test – Sample level C
 Salt spray testing – Sample level B
 If the maximum number of defective products is above the specified amount, then
the supplier shall advise Principal of the corrective action/ Principal reserves the
right to reject the batch until a corrective action has been approved.
3.2.2 Visual Examination
 The cured PTFE coating shall be free from runs, sags, misses or other defects
likely to compromise coating performance or affect thread fit.
 The Manufacturer shall verify if the manufacturing tolerance is adequate to
accommodate the proposed coating thickness without interfering the fit of the nut
by a method of trial fitting, thread accuracy shall be such that all plated / coated
nuts of particular size can be hand threaded onto the full length of all plated /coated
bolts of that same size.
 Nut threads shall be coated and nuts shall be tapped oversize to provide a class 2
fit for the coated bolt and nut assembly.
3.2.3 Thickness testing:
 The coating thickness test shall be in accordance with ASTM D 7091.
3.2.4 Hardness testing:
 The bolting components shall be subjected to a hardness test in accordance with
ASTM D 3359. The test shall be carried out on the bolt ends and nut faces.
 The coating hardness shall be grade 2H minimum.

3.2.5 Solvent test:

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 Solvent double rub test shall be performed using the standard procedure defined
by ASTM D 5402.
 A total of 20 double rubs shall be used. Removal of top coat to expose the
underlying base coat shall indicate inadequate cure.
3.2.6 Adhesion test:
 The coating adhesion test shall be carried out in accordance with ASTM D 3359,
method A “ X cut tape test:” The test shall be carried out on the bolt ends and nut
faces of test bolts or on test plates prepared as agreed for each batch.
 The coating adhesion shall have a rating of 4 (or) better.
3.2.7 Salt spray test:
 A corrosion resistance test for PTFE coat over Zn-Ni plated bolts shall be carried
out in accordance with ASTM B117 (salt spray test) for the time duration of 1000
hrs (minimum).
Coating records shall be integrated with certification records for the overall bolting
manufacture.
3.3 Bolting Colour coding Table:
The PTFE coating shall be colour coded as below :
Material Colour code
Alloy steel bolting to ASTM A 193 B7 and nuts to ASTM A 194 - Blue
2H; Zn- Ni plated + PTEFE up to 200°C.

Low temperature alloy steel bolting to ASTM 320-L7/L43 and nuts Black
to ASTM 194-4; Zn-Ni plated + PTFE up to 200°C.
Alloy steel bolting to ASTM A 193 B7M and nuts to ASTM A 194 - Green
2HM; Zn- Ni plated + PTEFE up to 200°C.

Low temperature alloy steel bolting to ASTM 320- L7M and nuts Yellow
to ASTM 194-7M; Zn-Ni plated + PTFE up to 200°C.
Alloy steel bolting to ASTM A 193 B8M Class 2 (strain hardened Red
316 SS) and nuts to ASTM A 194 -8M; Zn- Ni plated + PTEFE up to
200°C.
The standard stamping required by the material specification shall be legible after
the bolting components have been plated or coated with PTFE.
3.3 Certification
The producer or supplier shall provide certification in accordance with ISO 10474 type 3.1.
or EN 10204 type 3.1 that the finish was produced and tested in accordance with this
specification and found to meet the requirements. A report of the test results shall be
furnished.
A test report shall be submitted with the certificates, that includes the following information:
 A reference to this specification.
 A reference to test method(s) used
 The location(s) of the test area(s) on each specimen
 The quantity of specimen tested
 The name of the operator and testing laboratory
 The date(s) on which the test(s) were performed.
 Any circumstances or conditions thought likely to affect the results or their validity
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 Any deviation from the test method specified

 The quantified results of the test(s)
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PART IV REFERENCES

In this MESC SPE, reference is made to the following publications:

NOTES:
1. Unless specifically designated by date, the latest edition of each publication shall be used, together with any
amendments/supplements/revisions thereto.
2. Most of the referenced external standards are available to Shell staff on the SWW (Shell Wide Web) at
http://sww.shell.com/standards.

SHELL STANDARDS
ALLOY AND SS STEEL BOLTS TO ASTM A193 MESC SPE 81/001
CARBON AND ALLOY STEEL NUTS TO ASTM MESC SPE 81/002
A194

AMERICAN STANDARDS
Standard Specification for Alloy-Steel and Stainless Steel ASTM A 193
Bolting Materials for High Temperature or High Pressure
Service and Other Special Purpose Applications
Standard Specification for Carbon and Alloy Steel Nuts ASTM A 194
for Bolts for High Pressure or High Temperature Service,
or Both
Standard Specification for Alloy-Steel and Stainless Steel ASTM A 320
Bolting Materials for Low- Temperature Service

Standard Specification for Electrodeposited Coatings of ASTM B 841 – 99 (R 2010)

Zinc Nickel Alloy Deposits
Standard Practice for Fastener Sampling for Specified ASTM F 1470
Mechanical Properties and Performance Inspection
Standard Practices for Producing Films of Uniform ASTM D 823
Thickness of Paint, Varnish, and Related Products on
Test Panels
Standard Practice for Nondestructive Measurement of Dry ASTM D 7091
Film Thickness of Nonmagnetic Coatings Applied to
Ferrous Metals and Nonmagnetic, Nonconductive
Coatings Applied to Non- Ferrous Metals
Standard Test Methods for Measuring Adhesion by Tape ASTM D 3359
Test
Standard Practice for Assessing the Solvent Resistance ASTM D 5402
of Organic Coatings Using Solvent Rubs
Standard Practice for Operating Salt Spray (Fog) ASTM B 117
Apparatus
Issued by:
American Society for Testing and Materials
1916 Race Street, Philadelphia
19103, USA
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EUROPEAN STANDARDS
Metallic products - Types of inspection documents EN 10204
Issued by:
Commité Européen de Normalisation
Secrétariat Central
Rue de Stassart 36
B-1050 Brussels, Belgium

Copies can also be obtained from national standards organizations.

INTERNATIONAL STANDARDS
Steel and Steel Products - Inspection Documents First ISO 10474
Edition; (Corrected and Reprinted - 1992)
Issued by:
ISO Central Secretariat
1, ch. de la Voie-Creuse
Case postale 56
CH-1211 Genève 20
Switzerland
Copies can also be obtained from national standards organizations.