API RP 5L2:2002 pdf download

API RP 5L2:2002 pdf download.Recommended Practice for Internal Coating of Line Pipe for Non-Corrosive Gas Transmission Service.
4.4.2.7 Pot Life
Any material which has exceeded its pot life shall be rejected.
4.5 CLEANING OF PIPE
4.5.1 General
The cleaning shall be of sufficient quality to allow a firm continuous bond of the cured coating to the pipe, and should be performed immediately preceding the application of the coating material. Surface conditioning, such as grinding, shall result in pipe surface finish compatible with cleaning requirements. The cleaning method used (wet, brush, or abrasive cleaning) is at the applicator’s oion, unless the purchaser specifies a specific method. If the purchaser specifies abrasive cleaning, the degree of cleaning (e.g., Sa 2’/2) shall also be specified.
4.5.2 Degree of Cleaning
All loose mill scale and rust, water, oil, graphite, grease, marking materials, and other foreign materials that adversely affect the quality of the coating shall be removed from the surface to be coated.
4.5.3 Wet Cleaning
When wet cleanmg is performed with detergents, this process shall be immediately followed by sufficient rinsing with clear water to remove all harmful residue of any cleaning agents or detergents.
4.5.4 Drying
Removal of water may be accelerated by heating, but in no case shall this heating adversely affect the metallurgical properties of the steel, or deposit surface contaminations. Pipe surface shall be thoroughly dry before application of coating material.
4.5.5 Dry Cleaning
4.5.5.1 Method
Dry cleaning methods are brushing or abrasive blasting of the pipe. All components of the cleaning machine that enter the pipe shall be clean to prevent the deposition of grease, dirt, or other foreign material on the cleaned pipe surface.
4.5.5.2 Cleaning Machine Brushes
The cleaning machine brushes should be maintained at even pressures on all surfaces of the pipe interior to ensure adequate cleaning of the weld and adjacent areas. Burnishing of pipe surfaces should be avoided.
4.5.5.3 Cleaning and Coating
The cleaned surface shall not be allowed to deteriorate prior to the coating application. Cleaning and coating shall be done in separate stages to permit surface examination and prevent coating contamination.
4.5.6 Use of Air
Clean air may be used to accelerate drying and cleaning.
4.6 COATING OF PIPE
4.6.1 Equipment
4.6.1.1 Air Atomization
Air atomization application is not permitted under this Recommended Practice, except as permitted in 4.7.3.
4.6.1.2 Filters
Adequate filters shall be present in the equipment to ensure that foreign substances or detrimental particles are not carried to application assemblies.
4.6.1.3 Pressure Gauges
The coating material line to the spray guns should be equipped with a pressure gauge. For accurate pressure readings on airless spray unites, the pressure gauge should be equipped with a pulsation dampener. The location of this gauge should be downstream of all pressure drop causing devices, as near to the gun tips as is practicable.
4.6.2 Temperature of Pipe Surface
The temperature of pipe at time of application shall not exceed 150°F (66°C), or be less than 50°F (10°C).
4.6.3 Thickness of Coating
4.6.3.1 Dry Film Thickness
The minimum dry film thickness of the cured coating should be specified by the purchaser at the time the order is placed. Where no minimum thickness is specified, the minimum dry film thickness shall be 1.5 mils (38 microns).
4.6.3.2 Wet Film Thickness
The supplier shall recommend the range of wet film thickness that will be necessary to produce the required dry film thickness. This applies to coating material that has been thinned to proper application viscosity.
4.6.3.3 Pipe Ends
The purchaser should specify an internal cutback distance, if required. Suitable means shall be used to prevent depositing coating material on bevels and lands. Coating material depos-
ited on bevels and lands of the pipe ends or in cutback areas shall be removed immediately after coating.
4.6.4 Protection of Uncured Coating
Coating shall be applied in a covered or enclosed space shielded from high winds, blowing dust and dirt and inclement weather. Protection from these conditions shall be provided until the coating is tack free.
4.6.5 Acceleration of Initial Cure
Heat may be used to accelerate cure, providing it produces no adverse effects to the pipe or coating.