Published on 23 Apr 2019 by Tadd Pham
This quick reference is to provide guideline on the minimum necessary for making temporary leak repairs to process piping. This quick reference should be followed when making on-line repairs to piping components containing materials that could cause injury/illness to facility personnel, equipment damage, damage to the environment or community, or injury/illness to non-essential personnel.
Although the goal at any particular facilities is to operate in a leak-free environment, it is anticipated that, occasionally, piping leaks will occur. When this happens, a decision must be made as to how that leak will be repaired. The hierarchy for repair of piping leaks will be as follows:
- Shutdown the affected part of the process and isolate the leak, following site line break and lock, tag and try procedures. Replace or permanently repair the section of piping that is leaking, per the facility piping code and API 570.
- Shutdown the affected part of the process and isolate the leak, following site lock, tag and try procedures. Conduct a temporary leak repair.
- Continue to operate the process and make a temporary leak repair with the system at process pressure and temperature.
If it is determined that the repair must be done while the piping is still at process pressure and temperature, precautionary measures must be taken to ensure the safety of those making the repair. Leak repairs may only be performed while the equipment remains at process pressure and temperature if:
- Adequate safeguards are practical and can be provided, and
- A work permit and a written safety procedure must be prepared with due consideration for all the unusual conditions that are inherent in repairing an active leak.
A temporary leak repair is not intended to provide a long-term solution to leaking process lines. Temporary leak repairs should be performed when other options are not available and it has been determined that the repair can be performed safely, without putting those involved in the repair at risk.
Temporary leak repairs are considered a change of design and, therefore, require that a "Temporary Change of Design Authorization Form" be completed and approved by Operating Unit Personnel, HSE and Operations Managers.
Once the temporary repair has been made, plans must be put in place to ensure that a permanent repair can be made at the next planned shutdown for maintenance or sooner, if possible. The definition of “temporary” will be different for each case and the condition of the leaking component must be considered when deciding how long temporary is to be. The potential hazard due to a leak must be considered when determining this time period. An inspection frequency must be established to perform a visual inspection of the leak site until the leak can be permanently repaired.
Temporary leak repair is the repair of a leaking pipe and its components by means of clamping, banding, sealing and/or enclosing the leak. Repairs such as these are not intended to be permanent and the temporary repair should be replaced with a permanent repair as soon as possible.
The intent of this guideline is that:
- Temporary leak repairs will be conducted as a last resort
- The piping component to be repaired will be visually evaluated and ultrasonic thickness measurement used to determine that it is worthy of repair
- The working surface that those making the repair will be working from is safe with adequate access and egress
- PPE requirements will be based on the material inside the piping and will be the same as line break requirements
Planning and Preparation
- Selection of Leak Repair Provider - Choosing the method of repair should be done with the advice of the leak repair specialist (e.g. repair contractor) who will do the work.
- Selection of Repair Method - After the leak repair method has been selected, a meeting should be set up with operating unit personnel, including representatives of engineering, maintenance and production supervision. At this meeting, the leak repair specialist should present the proposal and seek agreement with all parties. When agreement has been reached, the repair safety checklist must be completed.
- Leak Repair Procedure Authorization - A work permit is required, along with a completed and approved repair safety checklist, before any process piping is repaired under pressure. The work should be approved by the operating unit maintenance and production supervision. The Change of Design Authorization Form must be completed and authorized.
- Work Environment - The work area around the piping to be repaired must provide adequate room for people to work, good footing, and unobstructed access and egress. The type of PPE that will be required must be considered when making this evaluation. The equipment must be located such that the work can be performed without having potential leaks from the piping/equipment dripping or spraying on the workers. Steps must be taken to direct liquid/gas/fume from process material away from people working on the equipment. Fire or toxicity hazards must be addressed by containment, ventilation, diking, dilution, etc.
- Process Material - When determining the feasibility of repairing a leak while the piping is at process pressure and temperature, process material properties such as toxicity, flammability, corrosivity, and temperature must be taken into consideration. These must also be considered when specifying appropriate PPE for the task. The material(s) selected for repair must be compatible to the process, including the pressure and temperature of the process, for the term of the temporary repair.
- Operating Conditions - Operating temperature and pressure must be determined prior to starting work on the repair so that the maximum safe pressure for doing work can be calculated. These conditions should be monitored throughout the repair to ensure that safe levels are not exceeded at any time.
- Materials of Construction - Materials of construction of the piping component must be identified. All metallic materials for pressure-containing parts, including bolting, should be in accordance with ASME Code Section VIII, Division 1 or ANSI B31. 3 or applicable standards. The leak repair specialist should select the sealant and injectable valve packing materials. Operations/Materials engineer should review and approve all such selections.
- Safety Requirements - The safety of the employees involved in the repair being done and employees who may be in the vicinity of the repair is the first priority in ensuring a successful repair. Consideration must be given to compatibility of materials being used, safe operating conditions maintained, providing a safe work environment for repair personnel, including access and egress and personal protective equipment requirements.
- Repair Review - The guideline to be used to repair the piping components and all safety precautions should be reviewed with those performing the work prior to starting work. The review should include a copy of the work permit and the completed checklist.