UKOOA - United Kingdom Offshore Operators Association
UKOOA 1.16 Fibre Reinforced Plastics (FRP) for Use Offshore
In the event of a conflict among the above listed standards or between the standards and other instructions listed in the specifications and drawing, it should be the Suppliers responsibility to notify the Buyer in writing for a resolution of the conflict prior to starting work.
The application, design, procurement, installation and repair of fiberglass piping systems for use in petroleum related applications with pressures greater than 6.9 MPa (1000 psig) should be in accordance with requirements of this specification, unless superceded by more stringent local regulations.
The manufacture, quality control, and inspection of high-pressure fiberglass pipe covered in this specification should be in accordance with API SPEC 15HR. Any deviations from the requirements of API SPEC 15HR should be approved by Buyer.
3.1 Resins and Curing Agents
Selection of Resins and Curing Agents
The selection of resins and curing agents should be based on fluid compatibility, intended service life, maximum operating temperature and costs.
- All these factors are affected by methods of fabrication and installation, cure, application temperature, and stress involved.
- The manufacturer should state the resin type, curing agent, and procedure used for the pipe and fittings.
- Proper considerations should also be given to the compatibility of the resin with the external service fluids and other chemicals and environmental conditions that contact the pipe and the duration of the contact.
The manufacturer should specify the method and materials to be used for curing.
- Curing should be done in a controlled environment in order to produce optimum properties of the thermoset.
- Consistency of the properties should be verified by mechanical property testing and the extent of curing or crosslinking should be checked using differential scanning calorimetry (DSC), infrared spectroscopy (IR), or mechanical testing. For DSC testing API SPEC 15HR should be followed.
- Typically the same curing process should be followed for all pipes, joints, connections etc.
- If different materials or curing techniques are used for accessories other than pipes, their performance rating should exceed that of the pipes. These should also be checked for the extent of curing or crosslinking and consistency of mechanical properties.
3.2 Joining System
The selection of a joining system should be based on cost, complexity of the piping system, ease of installation, availability of experienced installers and pipe size.
- Commonly used joining systems are threaded and coupled (T and C) and integral joint (IJ) threaded.
- The standard thread design listed in API SPEC 15HR, Section 3.3.2, is API 8 round.
- Alternate connections listed in API SPEC 15HR, Section 3.3.3, commonly are course threads with elastomer seals. Significant installation time can be saved by using course-threaded pipe. However, proper positioning of the elastomer seal is critical to effective pressure containment. The Manufacturer's recommended joint makeup procedure should be strictly followed. No substitutions are allowed for thread lubricants, makeup tolerances or torquing requirements.
- The adhesive provided with the joining kit should be compatible with the thermosets in the pipe and the fitting.
- It should also be compatible with the chemicals that contact the piping.
- Similar to the piping case, effects of temperature on the chemical resistance should be considered.
- The manufacturer should provide curing requirements such as curing temperature, pot life, and other requirements essential in proper use of the adhesive.
Gasket/seals should be made of materials resistant to the specified contents of the fluid being conveyed.
- The gasket/seal material may be specified by Buyer, where experience dictates.
- The gasket/seal material may also be specified by the pipe manufacturer, supported by documentation demonstrating the material's suitability.
Similar to the fiberglass pipe, selection of the gasket/seal should depend on the operation temperature and chemical compatibility.
3.5 Surfacing Veils
- Surfacing veils may be employed to improve resistance of laminates to weathering, corrosion, and abrasion.
- The benefits of applying surfacing veils should be weighed against the added cost and the circumstances of the installation.
Though surfacing veils improve the performance of the fiberglass piping, it is not necessary for all applications. For example, generally a surfacing veil is not necessary for mild chemical services containing salt, solvents, and solutions of pH 2 to 13. In addition, service with low solid content may not require a surfacing veil. However, the maximum allowable solids concentration depends on the type, size, and shapes of solids. A decision should be made based on previous experience and manufacturer's recommendation.
3.6 Other Requirements
All components of the piping system (pipe, fittings, and jointing kits) should be supplied and/or recommended by the same manufacturer when possible.
4.1 Suitability for Use
Piping purchased and installed in accordance with the appropriate sections of this specification is suitable for use in the following services:
- Water disposal and injection facilities (most common application)
- Produced and fresh water handling and transfer
- Multiphase crude, water or gas gathering and/or transfer
Fiberglass pipe should not be used in single-phase crude service without prior approval from Buyer.
Typically, treated salable crude is transported in metallic pipe.
4.2 High-Pressure Use
- Use of fiberglass pipe at high pressures above ground should be avoided.
- If above ground use is necessary, exposed pipe should be isolated and/or barricaded.
- Above ground high-pressure piping is typically made of steel, with the transition from fiberglass to steel occurring at maximum burial depth.
- High-pressure gas pipes should not be used above ground.
5.0 Design of Piping Systems
The design of a piping system should take into account loading conditions including, but not limited to, static and dynamic forces, such as the following:
- Design pressure, maximum operating pressure and upset conditions
- Test pressure and testing methods
- Internal pressure-shocks or pressure-surges caused by sudden changes in pressure and/or velocity (water hammer). The speed of valve closure bears consideration.
- Maximum and minimum operating temperature limits. The piping manufacturer should be consulted for recommendations to handle operating temperatures lower than -29°C (-20°F) and greater than 65°C (150°F). The requisition engineer should consider the operating temperatures anticipated throughout the life of the piping system.
- Excessive loads from impact, falling objects or moving objects. Below grade piping may need to be sleeved at road crossings.
- Thermal loads due to expansion and contraction, as a result of changes in temperature. Expansion and contraction are normally no problem in underground piping systems. However, suitable anchors, ties, or other devices must be provided, as recommended by the Manufacturer, to resist end forces produced by fluid pressure or other causes. Some Manufacturers require thrust blocks at intersections and elbows in order to maintain their warranty. These thrust blocks prevent transmission of bending moments in the fittings.
- Solids content effect on fluid velocity
- Maximum fluid velocity is typically limited by the thermoset's resistance to erosion. Specific Manufacturer recommendations on erosional velocity limits should be used in sizing pipe diameters.
- Minimum fluid velocity limits to avoid solid particle settlement in the pipe should also be considered when sizing pipe diameter. Typical maximum velocity limits to avoid erosion problems range from 1.5 m/s to 3 m/s (5 ft/sec to 10 ft/sec). Typical minimum velocity to avoid solid settlement ranges from 0.5 m/s to 1 m/s (1.5 ft/sec to 3 ft/sec).
- Erosion can be controlled by the use of a liner inside the piping and joints.
- Service fluids and other chemicals that the pipe comes in contact with and the duration of the contact
- Environmental exposure
5.1 Other Considerations
- The selection of a code to design a piping system should be in accordance with EPT 09-T-04 for the intended service. Design of high pressure fiberglass piping systems should minimize the use of fiberglass fittings because of their excessively high cost compared to internally plastic-coated and internally cement-lined spools.
- Follow the guidelines given in UKOOA 1.16 specification for both onshore and offshore applications.
- Possibilities and consequences of buildup and discharge of static electricity in piping systems installed in gas hazardous areas should be given proper consideration in the design.
- Static electricity can be generated inside and outside the fiberglass pipe and other insulated metal components in the pipeline. Factors to consider are:
- Conductivity of pipe laminate
- Conductivity of fluid to be transported
- Flow rates and turbulence in the flow
- Interfacial area between the pipe and fluid
- Humidity in the vicinity
- Impingement of non-conductive media on the outside of the pipe
5.2 Performance of the Fiberglass Piping System in a Fire Situation
- Follow the guidelines given in UKOOA 1.16 .
- Factors to consider are:
- Blast endurance and wall thickness
- Protective coatings
- Protection of joints and supports
- Retention of pressure and flow
- Formation of steam traps
- Possibility of a jet fire
- Heat release and spread of fire
- Smoke emission
- Visibility and toxicity of the smoke
6.0 Installation and Repair
Handling, installation, system pressure testing, and repairs should be in accordance with API RP 15TL4 and the pipe manufacturer's recommended procedures.
- In no case should pipe be handled, installed, tested or repaired in a manner that would void the manufacturer's warranty.
- Underground installation should be in full agreement with the manufacturer's recommendations with proper soil and ground considerations.
- Adhesives should be compatible with the thermosetting resin in the pipes and fittings. They should be suitable for service up to the maximum rated temperature of the pipe and fittings.
- The manufacturer may be required to furnish a qualified on-site representative to witness and inspect the installation work by the contractor and to advise or train the contractor personnel, if necessary.
- The User should require the Manufacturer's on-site Representative to be present until both the Manufacturer and the User are satisfied that each lay crew is installing the pipe in a manner that will maintain the Manufacturer's warranty intact. The user may or may not be required to pay for this service (often depending on the length of time the Manufacturer's Representative is needed) and should incorporate this price in the material procurement document.
- The design and layout of the fiberglass pipe should take into account the needs for the service repair, and maintenance of the fiberglass pipe system.
- Depending on handling and use, fiberglass piping may require significant maintenance. It is recommended that the end User secures adequate resources for maintenance prior to specifying a fiberglass pipe and a manufacturer. For example, repair options for damage to a fiberglass pipe due to impact may vary substantially depending on the manufacturer, type of pipe, type of joining system and ambient conditions. The pipe manufacturer should exhibit an adequate pipe repair or replacement technique for the pipe chosen. Replacement parts and repair material should be readily available on site. It may also be necessary to train the maintenance personnel.
- Significant number of flange connections may be necessary at regular maintenance areas; for example, around pumps, compressors, etc.
6.1 Pipe Joints
- Pipe joints should be made in the presence of the Pipe Manufacturer or a Representative.
- Manufacturer(s) of pipe, joints, and adhesives should train the pipe joiners.
- Every joiner should make two joins of each kind (pipe-to-pipe, pipe-to-fitting, etc.).
- If any one of those joins fails the minimum pressure test, the joiner should be disqualified for the final job.
- The Manufacturer may retain the joiner and he/she may be reconsidered. This should not be repeated more than once for any joiner.
- Joints and connections are the most vulnerable spots in fiberglass piping. Though not apparent, they are more complex in fiberglass piping than metal piping. It is the apparent simplicity of fiberglass pipe connections that may result in joiners taking inadequate care during make-up. The Manufacturer's specified procedures should be followed at all times in order to ensure leak-free joints.
- In systems with numerous connections, pressure testing a portion of the system early in the installation should be considered, in order to verify that proper joint makeup is being performed.
- Prior to pressure testing, the middle portion of each jointed pipe length should be spotted with backfill, leaving the connections visible.
- Pressure testing generally should be conducted with fresh water to avoid environmental damage in the event of a leak or rupture. Testing should be carried out for a minimum of two hours or overnight, where practical. Each connection along the entire length being pressure-tested should be visually inspected for leaks. Pressure charting is not reliable for determining a successful test, due to temperature fluctuations and elongation of the line.
6.2 Component Ends
All component ends should be provided with suitable end-caps or covers to protect them from stray particles, ingress of dirt and damage due to impact and ultraviolet rays from sunlight. Such end-caps or covers should not be removed until the component is ready for installation.
Thermosets in fiberglass are hard and fragile materials. Therefore, threads on the joints, where loading of glass fiber may be less or even absent are fragile and can get destroyed by a harder impurity. Also, thermosets are susceptible to the sunlight (ultra violet rays) which can deform the threads or joining areas.
6.3 Other Requirements
- The safety of personnel and livestock around open ditches should be considered during installation.
- Painting of above ground installations is recommended for protection from ultraviolet degradation and for aesthetic considerations.
Repairs should be made only by trained personnel in accordance with the pipe manufacturer's recommended procedure(s), using only the pipe manufacturer's parts and materials.