1. INTRODUCTION
1.1 Scope
1.1.1 This Specification defines the requirements
for the internal coating of line pipe, with an epoxy based paint to:
·
provide a passive barrier to the
internal steel surfaces against corrosion prior to installation of the
submarine gas pipeline,
·
reduce friction and improve the flow
conditions in the gas pipeline.
1.1.2 This Specification covers the minimum
requirements to be met regarding the epoxy paint and paint film properties, the
physical performance requirements for the material, surface preparation, paint
application, inspection and testing of the internal epoxy paint coating.
1.1.3 The performance and long term behaviour of
the CONTRACTOR’s proposed epoxy paint system shall be demonstrated by test
data. The CONTRACTOR shall provide the
basic physical properties and performance test data to support the suitability
of its epoxy paint coatings at 75 microns nominal total dry film thickness, and
their expected behaviour with time under the service conditions addressed
herein.
1.2 Deviations
All deviations to this Specification
and other referenced Specifications or attachments listed in the Contract shall
be made in writing and shall require written approval by the COMPANY prior to
executing the work.
1.3 Reference
Documents
Except where otherwise stated in this
Specification, materials and work carried out shall be in accordance with the
latest edition (issued prior to the award of contract) of the following codes
and standards:
1.3.1 British,
European and International Standards
API RP 5L2 Recommended Practice for Internal
Coating of Line Pipe for Non-Corrosive Gas Transmission Service
BS 2451 Specification for chilled
iron shot and grit
BS 3900 Methods
of Test for Paints
BS5493 Code of Practice for
Protective Coating of Iron and Steel Structures against Corrosion
BS 7079 Preparation
of Steel Substrates before Application of Paints and Related Products
Part A1 Specification
for rust grades and preparation of uncoated steel substrates after overall
removal of previous coating.
ISO 5151 Paints and Varnishes – Determination of Volatile
and Non-Volatile Matter
ISO
1524 Paints and
Varnishes – Determination of Fineness of Grind
ISO 2431 Paints and Varnishes – Determination of Flow Time
by a Flow Cup
ISO
2811 Paints and
Varnishes – Determination of Density
ISO 2813 Paints and Varnishes – Measurement of Specular
Gloss of Non-Metallic Paint Films
ISO 8501-1 Preparation of Steel Substrates before Application of
Paints and Related Products – Visual Assessment of Surface Cleanliness –
Part 1 : Rust grades and preparation of uncoated steel
substrates after overall removal of previous coating.
ISO 8503-1 Preparation of Steel Substrates before Application of
Paints and Related Products – Surface Roughness Characteristics of Blast –
cleaned Substrates –
Part 1
: Specification and definitions
for ISO surface profile comparators for the assessment of abrasive
blast-cleaned surfaces
BS
EN ISO 9001 Quality Systems
ASTM
1650 Sampling and Testing
Shellac Varnish
SSPC Manual Steel structure Painting Counsel “Surface Preparation
Standards”
ASTM B117 Standard Test Method of Salt Spray Testing
API RP 5L2 Recommended Practice for Internal Coating of Line Pipe
for Non –Corrosive Gas Transmission Service.
ASTM 3359 Standard Test Methods for Measuring Adhesion by Tape
Test
1.3.2 Project
Specifications and Drawings
84506-60-30-2L-270 Specification for Handling, Storage
and Transportation of Linepipe
84506-60-30-2L-260 Specification for Pipeline Asphalt
Enamel Coating
84506-60-30-2L-250 Specification for Concrete Coating
Application
1.3.3 Other
References
Manufactures data sheets for selected
products.
2. TECHNICAL DATA
2.1 General
2.1.1 The following information shall be taken into
account for determination of the suitability of the CONTRACTOR’s epoxy paint
system:
-
the
carbon steel line pipes shall be assumed to be subjected to a maximum of 24
months exterior exposure at a coastal port prior to installation.
-
The
total dry firm thickness of the epoxy paint coatings shall be 75 microns
nominal and shall be applied in a single application onto grit blasted surfaces
to Sa 2½ with an anchor profile (surface roughness) of 50 microns typical.
-
During
service, the epoxy paint coatings will be permanently subjected to contact with
natural gas at a pressure of up to 1200 psi and temperature of up to 50oC
and flowing at a velocity of 0.33 m/s. The thin epoxy paint film shall not
disintegrate as flakes or contaminate the natural gas when in service.
2.1.2 The CONTRACTOR shall submit to the COMPANY
for review and approval physical properties and performance test data to
support the suitability of its epoxy paint coatings at 75 microns nominal total
dry film thickness, and their expected behaviour with time under the service
conditions specified herein, including the mechanism for paint breakdown and
degradation.
The CONTRACTOR shall also show if there
is any effect of nitrogen on the integrity of the applied epoxy paint coating
system during leak testing of the pipeline.
2.1.3 A
manufacturer’s representative shall be present for the start of the work.
3. MATERIALS
3.1 Description
3.1.1 The epoxy based paint shall be two-pack
products formulated to provide the specified film build without sagging or
running, and also to provide a passive barrier to satisfy the requirements of
this Specification. Pigments shall be
selected to provide maximum resistance to the environmental and service
conditions addressed in this Specification.
3.1.2 The Coating
materials shall consists of the following:
- an epoxy
resin base with pigments, extenders, additives and organic solvent,
- an epoxy
aliphatic/cycloaliphatic amine or polyamide curing agent.
3.1.3 The components shall have a polar high
molecular weight with very low vapour pressure and diffusion rate within the
paint film.
3.1.4 The base and curing agent shall not contain
fatty acids, oil, paraffin, chlorinated platicizers, fatty acid esters or other
substances which can contaminate the natural gas.
3.1.5 The pigment shall include sufficient rust
inhibitor to pass the salt water spray test in accordance with ASTM B117 and
API RP 5L2 Appendix 2 for a minimum of 500 hours. The pigment and the extender shall not react
chemically with the curing agent.
3.1.6 The volume solids of the epoxy paint shall be
at least 38%, when measured in accordance with API RP 5L2 Appendix 1.
3.1.7 The paint shall be of the high gloss type,
minimum 50 measured on air cured coating at an angle of 60o in
accordance with ISO 2813.
3.2 Qualification
of Coating Materials
3.2.1 The coating materials shall be fully tested
in accordance with the requirements of API RP 5L2 Section 3 and certified to be
in compliance with the acceptance criterion specified API RP 5L2 Table
3.5. All performance testing shall be
carried out with the dry film thickness according to the requirements of this
Specification.
The performance testing shall also
include a 100% methanol and 100% tri-ethylene glycol immersion test at room
temperature for 5 days. The epoxy paint
coating shall be free of blisters after removal from the 5 day immersion test.
Acceptance of the paint materials shall
be subject to review of the paint manufacturer’s performance data and materials
test data, as well as the CONTRACTOR’s paint coating procedures, which shall
demonstrate that the proposed paint coating system is suitable for use in
service conditions as detailed in this Specification.
3.2.2 The Selected paint material manufacturer
shall keep available a technical representative for provision of advice,
instruction and assistance to the CONTRACTOR for the coating duration. The technical representative shall be fully
familiar with the requirements of this Specification and with the application
characteristics of the epoxy paint coating system under consideration.
3.2.3 The CONTRACTOR shall obtain the epoxy paints
and thinners for the internal coating of line pipes from paint manufacturers
approved by the COMPANY.
3.3 Material
Supply, Handling and Storage
3.3.1 The paint materials shall be delivered to the
site, or the CONTRACTOR’s premises, in the original containers with label
intact and the seals unbroken, and accompanied with certification of the
physical properties addressed herein of each batch of coating materials
shipped.
An infra-red spectre shall also be
included in the paint manufacturer’s testing procedures and detailed in the
batch certification.
3.3.2 Notice shall be taken at all times of the
paint manufacturer’s instructions in respect of handling, storage, shelf life, mixing
and thinning, as well as method of application.
3.3.3. Paint which has livered, gelled or otherwise
deteriorated during storage, shall not be used.
3.3.4 The manufacturer’s safety data sheets on
coating materials to be applied shall be obtained and shall be made
continuously available at the work place.
4. PROCEDURES
4.1 Coating
Procedures
4.1.1 The CONTRACTOR shall submit detailed method
statements and procedures which shall cover as a minimum all the activities
below to demonstrate to the COMPANY that its proposed coating materials and
coating process fully meets with the requirements of this Specification. These
documents must be approved by COMPANY before commencement of work.
a) Line pipe
handling, storage and inspection at all stages of application work.
b) Line pipe surface
preparation including abrasive details, removal of steel defects and methods of
surface cleaning and surface profile measurement.
c) Complete details
of the coating materials together with quality control, storage of materials,
manufacturer’s certification and safety sheets.
d) Application of
epoxy paint including details of film thickness, method of application.
e) Cure time
f) Inspection and
testing including instrument and equipment types, frequency and acceptance
criteria.
g) Details of instrument
and equipment calibration methods including relevant standards and examples of
calibration certificates.
h) Complete details
of inventory of laboratory and equipment.
i)
Quality control procedures, including
methods of record keeping, batch identification, details of personnel for all
aspects of the work.
j) Coating repair
procedures and acceptance criteria for repairs and rejection.
4.2 Procedure
Qualification
4.2.1 The internal epoxy coating system and
detailed coating procedure, shall be qualified, by coating at least ten (10)
pipe lengths prior to full coating production.
The COMPANY will confirm the wall thickness(es) of the carbon steel line
pipes to be used for the procedure qualification trial(s) (PQTs).
4.2.2 Qualification of the coating materials shall
be carried out in accordance with the requirements of Section 3.2 herein.
The following properties of the
components shall also be determined:
-
An infra-red scan of the mixed paint components.
-
Specific gravity of the epoxy resin base, curing agent and
the mixed paint components in accordance with ISO 2811.
-
Viscosity of the epoxy resin base, curing agent and the
mixed paint components in accordance with ISO 2431.
-
Fineness of grind of the mixed paint components in
accordance with the ISO 1524, Hegman scale.
-
Ash content of the mixed paint components in accordance with
ASTM 1650.
-
Volatile and non-volatile matters in the mixed paint in
accordance with ISO 1515
4.2.3 Inspection and testing of the applied
internal epoxy paint coating shall be carried out by the CONTRACTOR to prove
compliance with the requirements this Specification.
4.2.4 All qualification testing shall be
satisfactorily completed prior to full factory application. The CONTRACTOR shall not coat any other pipe
lengths before tests results have been obtained and approved by the COMPANY.
Subject to final acceptance of the PQT
test results, all the coated pipe lengths used for the PQT(s) shall form part
of the coated pipe assignment.
5. PROCESS REQUIREMENTS
5.1 Surface
Preparation
5.1.1 Prior to surface preparation and painting of
the internal surfaces of the line pipes, the CONTRACTOR shall be responsible
for the protection of the bevelled ends and any protective coatings on the
external surfaces of the line pipes.
5.1.2 Unless specifically excluded herein, the
internal steel surfaces of the line pipes shall be prepared by dry abrasive
blast cleaning prior to painting.
Preparation methods and procedures for
surfaces to be painted shall remove all foreign matter, surface irregularities
and contaminants to bring the surface to the specified standard of cleanliness
prior to the application of the paint coatings.
5.1.3 Before any blast cleaning operation
commences, every pipe shall be 100% totally cleaned with a solvent or by high
pressure steam to remove any oil, grease or other contaminants on the surfaces
to be paint coated. Pipes which have
been exposed to salt spray shall be washed with fresh, potable water to remove
any contamination from the pipe surfaces.
Salt contamination on the surface shall be measured by checking the
conductivity using a Soluble Salt Detector (SCM 400 model or equivalent). The sodium chloride content shall be below 10
mg per m2. Solvent cleaning
shall be carried out in accordance with SSPC-SP1-91 “Solvent Cleaning”.
5.1.4 Surfaces, such as the bevelled ends of the
pipes, which are not to be primed shall be masked to protect from damage by
abrasive blast cleaning.
5.1.5 Blast cleaning shall be carried out using dry
steel grit HG 40 to SAE J444 to provide a visual finish standard of cleanliness
of Sa 2½ in accordance with BS 7079 Part A1 or ISO 8501-1. All blast cleaning shall be performed under
cover.
5.1.6 The type and size of abrasive, which shall be
free from impurities, shall be steel grit selected to give a surface amplitude
/ anchor profile of 50-75 microns with a maximum of 100 microns. Surface roughness of the blast cleaned steel
substrates shall be of “medium” grade equal to Segment 2 of an approved ISO
surface profile comparator Type G conforming to ISO 8503-1 Part 1. Surfaces being blast cleaned shall not be
impaired by excessive blasting and the surface profile/roughness shall be given
close attention.
Re-usable abrasive shall be regularly
checked and sieved to remove fines and contamination.
5.1.7 All blast cleaned surfaces shall be free from
surface irregulaties such as slivers, hackles or laminations which would impair
the application or performance of the finished paint coating. Where the CONTRACTOR considers extensive
grinding is necessary to remove surface defects such pipes shall be reported to
the COMPANY for approval.
5.1.8 Any area in excess of 50 cm2 which
is subject to excessive remedial or grinding work shall be locally re-blasted
and the resulting wall thickness checked in the presence of the COMPANY to an
approved method.
5.1.9 Any remedial or grinding work must not reduce the pipe wall thickness,
in the areas treated, below the minimum requirements of the line pipe
specifications referenced herein.
5.1.10 Any pipe found to have a reduction in wall
thickness or defects which exceed the levels permitted in the line pipe
specifications detailed herein shall be quarantined for examination by the
COMPANY and no subsequent action taken without the agreement of the COMPANY.
5.1.11 The CONTRACTOR shall have available for review
by the COMPANY full details of the proposed abrasive.
5.1.12 Spent abrasive shall be completely removed from
the prepared surface by either vacuum cleaning and/or still brushing.
5.1.13 Blast cleaning shall not be carried out in areas
close to painting operations and/or wet coated surface in order to prevent dust
or grit contamination.
5.1.14 The compressed air supply used for blasting
shall be free from deleterious amounts of water and oil.
5.1.15 No acid or inhibitor solutions shall be used on
steel surfaces after they have been blast cleaned.
5.2 Environmental
Conditions
5.2.1 Surface preparation shall not take place at
air temperatures below 5oC, when the relative humidity is greater
than 85%, or when the metal surface temperature is less than 3oC
above the ambient dew point, or later in the day than can be prime coated
before the end of the working period.
5.2.2 Blast cleaned steel surfaces shall be kept
free from any contamination and shall be completely free from blast residues,
dust or grit.
5.3 Paint Coating
Application
5.3.1 All application procedures and equipment
shall be available for review by the COMPANY.
5.3.2 Painting shall only take place under
conditions recommended by the paint manufacturer.
5.3.3 Coating application
shall be airless spray unless otherwise specified.
5.3.4 The epoxy paint shall be applied to the blast
cleaned internal surfaces of the line pipes as soon as practicable after
completion of blast cleaning.
In no case shall the paint be applied
to blast cleaned surfaces showing evidence of fresh rusting, contamination
(including condensation), or when the specified standard of cleanliness is less
than Sa 2½. Blast cleaned surfaces shall
be paint coated within 4 hours after blasting completion.
5.3.5 The epoxy paint shall be applied in a uniform
manner without runs, sags or other blemishes.
Unless specified elsewhere, the epoxy paint coating shall be continuous
for the full length of each line pipe, except for an area at each end of 50 +
10 mm. The nominal dry film thickness of
the applied epoxy paint coating shall be 75 microns.
5.4 Application
Equipment
5.4.1 The spray equipment and nozzle sizes shall
meet the recommendations set forth by the paint manufacturer for the epoxy
paint. Lines and pots shall be
thoroughly cleaned before adding new materials, and only the paint
manufacturer’s recommended cleaning agents shall be used.
Spray method including overlap, gun
adjustment and direction of spray shall be in accordance with the paint
manufacturer’s recommendations.
6. INSPECTION AND TESTING OF PAINT COATING
6.1 General
6.1.1 The CONTRACTOR shall be responsible for all
inspection and quality control functions necessary to achieve coating standards
in accordance with this Specification.
6.1.2 The CONTRACTOR shall record on appropriate
tally sheets the identification markings of each individual line pipe (so that
manufacturing heat and piece numbers are not lost during the paint coating
process) prior to surface preparation of their external surfaces. The information shall subsequently be
transferred on to the epoxy paint coating.
6.1.3 It is the CONTRACTOR’s responsibility to
ensure that sufficient tests are carried out to show that the coatings comply
with this Specification. The COMPANY
reserves the right to carry out any additional tests at random to ensure
compliance and the CONTRACTOR shall have
suitable test-equipment available for the COMPANY’s use.
6.1.4 A full reporting/recording system shall be
maintained by the CONTRACTOR who shall log daily the following data:
-
Air and steel temperatures
(min twice per working shift)
-
Relative humidity
(min twice per working shift)
-
Surface profile and roughness
-
Viscosity of the ready to use paint
-
Wet and dry paint film thickness
measured
-
Paint batch no.
-
Painting progress
-
And any other information pertinent to the work
6.1.5 It
is the CONTRACTOR’s responsibility for the supply of all test equipment
suitable for the inspection requirements. CONTRACTOR will ensure that all test
equipment is certified and calibrated in accordance with the manufacturers
requirements.
6.2 Production
Inspection and Acceptance
6.2.1 The inspection and testing requirements,
procedures, frequencies and limits of acceptance of the internally coated pipe
and the methods of testing during production of the internal coating shall be
according to API RP 5L2 Section 5.
6.3 Inspection of
Prepared Surfaces
6.3.1 All blast cleaned surfaces shall be visually
inspected to check for conformance to the specified standard of cleanliness
immediately prior to painting. In
addition to visual examination, the roughness of each pipe surface shall be assessed using an
approved ISO surface profile comparator, and also random measurements of blast
/ anchor profile shall be made at a minimum frequency of one every 20 pipes,
using Testex tape.
6.4 Visual
Inspection of Painted Surfaces
6.4.1 All painted surfaces shall be visually
examined to check for deleterious film defects e.g. runs, sagging, wrinkling,
discontinuity in the paint coating, contamination etc. The requirements of this Specification and
the recommendations of BS 5493 shall be followed in the rectification of such
defects.
6.5 Coating
Thickness Measurement
6.5.1 Wet film thickness measurements shall be made
throughout the course of application in order to ascertain the adequacy and
uniformity of thickness.
6.5.2 Dry film thickness measurements shall be
checked on every pipe after the paint coating has cured. Thickness measurements shall be taken at five
locations in two different planes at regular intervals along each pipe. All measurements shall be recorded for each
painted pipe on the inspection record sheets.
The dry film thickness of the paint
coating shall be within a range of + 25 microns to – 10 microns of the nominal
film thickness of 75 microns.
6.6 Additional
Tests
6.6.1 100% pin hole detection using a 9V wet sponge
tested and procedures approved by the COMPANY shall be carried out on all paint
coatings. The paint coatings shall be
free from pin holes and defects.
6.6.2 All paint coatings shall be tested for
adequacy of cure using a MEK solvent wipe at a frequency of 1 per 10
pipes. The test shall consist of a one
minute wipe with a soft white MEK soaked cloth.
Confirmation of cure shall reveal only slight traces of paint on the cloth.
6.6.3 Paint adherence
checks shall be in accordance with ASTM D. 3359
6.7 Rejected
Coated Pipe
6.7.1 Coated pipes which have been rejected when
tested shall require complete removal of the coating and shall be completely
recycled through the cleaning and coating process.
6.7.2 All pipe coating removal and re-coating shall
be the CONTRACTOR’s responsibility.
7. PAINT COATING REPAIRS
7.1 General
7.1.1 Repair of defective or damaged coatings shall
be accomplished in the same manner as the original coating in regard to surface
preparation prior to re-coating, unless alternative and equivalent methods are
defined within this Specification, or agreed by the COMPANY.
7.2 Insufficient
Thickness
In the event that a completely coated
surface is found to have insufficient coating thickness, this surface may,
subject to the COMPANY’s approval, receive an additional coat until the
specific thickness is achieved. The
COMPANY may alternatively require the surface to be blast cleaned and
re-coated. Surfaces to receive
additional coating shall be properly cleaned of all foreign matter or
contaminants and prepared as recommended by the material manufacturer.
7.3 Excess
Thickness
7.3.1 In the event that a coated surface is found
to have serious excessive thickness it shall be brought to COMPANY’s attention,
who will decide on the appropriate action to be taken.
7.4 Repair
Inspection
7.4.1 Coating repairs shall be subject to the
visual, thickness and holiday testing requirements defined in this
Specification.
7.4.2 If a repair fails to satisfy the above
requirements then the pipe shall be rejected and subsequently stripped, blast
cleaned and reprocessed.
7.4.3 COMPANY reserves the right to reject pipe
which it considers to have excessive number of repaired areas.
8. HANDLING
8.1 General
8.1.1 Handling will be in accordance with
specification 84506-60-30-2L-270. Chains,
hooks or cables around the bare or coated pipe shall not be used.
8.1.2 At every stage of surface preparation and
coating application, the pipe shall be kept under cover and protected from the
outside environment.
8.1.3 A detailed handling, storage and
transportation procedure shall be submitted by the CONTRACTOR for the COMPANY
approval prior to commencing work.
Storage and handling shall be carried out in such a manner that damage
to the coating is avoided.
9. IDENTIFICATION MARKINGS
9.1 General
9.1.1 Delivered pipe will bear certain stenciled
identification on each length such as order number, specification and grade,
size and wall thickness and heat number.
In addition each pipe length will bear a sequential piece or joint
number die stamped on the weld bevel at each pipe end.
9.1.2 Prior to surface preparation operations which
would obliterate stenciled identification, the CONTRACTOR shall record the
information on appropriate tally sheets.
This information shall subsequently be transferred to the applied epoxy
paint coating.
9.1.3 The format of the tally sheets, information
to be recorded and methods to be employed shall be proposed by the CONTRACTOR
and approved by the COMPANY prior to commencement of production.
10. DOCUMENTATION
10.1 General
10.1.1 All data shall
be supplied in hard copy and in an electronic format.
10.1.2 The CONTRACTOR’s documentation shall be
designed to ensure full traceability of pipe and coating materials through all
stages of preparation, coating and testing.
10.2 Certification
Data
10.2.1 Certification data shall be compiled on an
ongoing basis in accordance with the requirements of the Contract.