Nace CP 1, Course Manual

Page: 349 / 535

RP0176-2003
NACE International
27
13.6.3 An air source that can supply a minimum of
0.85 m
3
/min (30 cfm) at 690 kPa (100 psig) at the noz-
zle for spraying operation should be available.
13.7 Typical Coating Systems in Use
13.7.1 Table 3 illustrates coating systems commonly
used in the atmospheric zone of offshore structures
and associated equipment. These systems are not
presented as recommendations, nor does the order
listed indicate preference or superiority of one system
over another. The selection of a coating system should
be based on the criteria outlined in Paragraph 13.4
and/or results from field experience and maintenance
programs.
Table 3: Typical Coating Systems Used in the Atmospheric Zone
(A)
Thickness
Coating System
µm mils
Inorganic zinc-rich self-cured primer 75 3
Epoxy tie-coat 50 2
High-build polyurethane 150 to 200 6 to 8
Epoxy intermediate and topcoat (2 coats) 250 10
Vinyl high-build intermediate coat 100 to 150 4 to 6
Vinyl topcoat (2 coats) 50 2
Epoxy intermediate coat 100 to 150 4 to 6
Vinyl acrylic or polyurethane topcoat 50 2
Co-polymer tie-coat 50 2
Vinyl high-build topcoat 150 to 250 6 to 10
___________________________
(A)
The specified number of coats and the thickness may vary among operators and manufacturers
13.7.2 Maintenance coatings must be compatible with
the original coating system.
13.7.3 The frequency and extent of recoating or
touch-up work to be performed depends on many vari-
ables, including the following items:
(a) Extent and location of corrosion damage on the
structure,
(b) Stress or loading of the affected structure
members,
(c) Danger of spills and leaks from production piping
and vessels,
(d) Cost of recoating work, including set-up charge,
(e) Cost of deferred production and any equipment
downtime during coating operations,
(f) Safety of personnel, and
(g) Appearance
factors.
13.8 Coatings for Production Equipment and Piping located
on Structures
13.8.1 For most equipment operating at ambient tem-
peratures, many of the systems listed in Table 3 are in
widespread use.
13.8.2 Some surfaces on heaters, compressors, or
other equipment may have elevated temperatures. If
coatings are needed on these surfaces, special high-
temperature coatings are available. Other processes,
such as metalizing, porcelainizing, or using ceramic
coatings, may also be considered.
13.8.3 For intricate shapes such as manifolds and
christmas trees, care must be taken to avoid applying
an excessively thick coating (see Paragraph 13.9.5).
13.9 Special Problems in Offshore Coating Programs
13.9.1 Thorough planning is necessary for applying
coatings offshore. The problems of logistics, accessi-
bility, scheduling, housing, and storage are more criti-
cal and far more costly than when applying coatings
onshore.
13.9.2 The structure to be coated should be surveyed
by representatives of the owner, supplier, and the con-
tractor to consider the following aspects of the struc-
ture:
(a) Accurate area measurements,
(b) Condition of steel,
(c) Protection of production equipment required,