DC pipe patches are growing trend.
A variety of reasons exist for using DC pipe patches (e.g., from not having skilled repair personnel available to not being able to isolate the piping system). However, even using the soft patch or EWARP requires work controls and quality assurance to ensure an effective, temporary repair.
Types of DC Pipe Patches
The EWARP is a strong, densely woven fiberglass tape, impregnated with resin. It has excellent adhesive qualities when applied to steel and copper materials, which makes it ideal for patching piping systems with a maximum pressure of 150 psi and a maximum temperature of 300 degrees Fahrenheit. The EWARP can be applied to fresh water (except potable water-inlet lines), salt water, hydraulic, and lubricating-oil piping systems. However, it cannot be used in steam and fuel piping. The shelf life for EWARP is two years; if the shelf life has expired, remove it from active inventory and use the expired packs only for training.
Another patch that has a maximum pressure rating of 150 psi is the soft patch, which often is used to temporarily repair small holes or cracks in low-pressure piping systems. Soft patches typically use a combination of rubber sheet material, rags, oakum, marline, wire, various size wedges, and canvas. According to NSTM 079, Vol. 2, soft patches are OK for low-pressure (not high-pressure) steam lines. The rubber sheet material will melt and stink, but it will vulcanize and make a tight patch. Don't use soft patches on gasoline or other flammable piping systems, because the slightest leak creates a fire hazard.
Quality Assurance and DC Pipe Patches
During combat or severe casualty situations, the pipe patch may leak because of the necessity to restore a critical piping system so a ship can continue its mission. Pipe patches applied to a leak on a piping system during normal ship operations require following procedures as strictly as during other maintenance procedures. A maintenance person must know what a technical work document is to ensure a leak-proof patch (especially for CHT systems), because the patch often remains in place from a week to months. Here are some references for pipe-patch procedures:
* NAVSEA SS-100-AG-MAN-010, Damage Control/Firefighting Equipment Layout Booklet
* NAVSEA S9086-CN-STM-020/CH-079V2R2, NSTM, Chapter 079, Vol. 2--Practical Damage Control
When DC pipe patches are used as a temporary repair, a departure from specification (DFS) is required. This requirement is especially important when the wall thickness of a pipe or pipe components falls below minimum specifications, and permanent repairs to restore the piping system to technical specifications aren't possible. The DFS is the mechanism used to document and resolve a lack of compliance with any authoritative document, plan, procedure, or instruction. Volume V, Chapter 8, of the Joint Fleet Maintenance Manual (JFMM) contains the definitions and processing procedures for a DFS. Before using a pipe patch and submitting a DFS, ask these questions to ensure you can use the pipe patch on the piping system:
* On what type of piping system will the pipe patch be applied?
* Is the pipe patch authorized for the piping system?
* What is the piping system's operating pressure?
* What is the temperature of the piping system?
* When does the shelf life of the EWARP expire?
* How long will it be until a permanent repair can be accomplished?
The last question is important since ship's maintenance teams are responsible for tracking approved departures from specifications and reviewing them before each upkeep period to establish fleet-maintenance activity/shipyard work requirements to clear each one.
Shipboard Allowance Requirements
Take care when using pipe-patching material for temporary piping-system repairs. Each patching kit only has a certain amount of available material, and the Surface Force Training Manual requires you to have all DC-repair-locker equipment on hand or on order. The pipe-patching-kit allowance-equipage list (AEL 2-880044268) has two EWARP kits, one size 1 (2-by-62 inches) and one size 2 (4-by-180 inches) listed. Also listed are the quantity requirements for soft-patch materials. The requirement for how many pipe-patching kits to have on hand is based on each ship-class DC tools and equipment AEL for the total number of kits required for each DC repair station.
While temporary pipe patches have become commonplace in the fleet, shipboard personnel need to be aware of the following key points:
* Pipe patches of any type applied to piping systems are temporary in nature and always require the submission of a DFS before placing the affected system back in service.
* Because these repairs are temporary, ships' personnel need to ensure timely completion of a permanent repair, which restores the system to original specifications.
* All work conducted on ships' systems require a technical work document. This document can range from a locally generated formal work package (FWP) to a more in-depth controlled work package (CWP), required for systems identified in the JFMM, Vol. V, Chapter 2.
* Damage-control personnel need to know the impact these DC pipe-patching kits have on their required shipboard inventory and manage this inventory accordingly.
While using temporary pipe patches cannot be avoided, long-term reliance on their effectiveness is unwise. Understanding the temporary nature of such repairs is key to ensuring that the proper quality assurance requirements are met, and that the permanent repair is planned and executed at the earliest convenient time.
The author is the force damage-control officer.
* NSTM 505, Piping Systems
* NSTM 079, Vol. 2, Practical Damage Control
* ComFltForComInst 4790.3, REV B, Joint Fleet Maintenance Manual
* ComNavSurForInst 3502.1D, Surface Force Training Manual
By Lt. Paul Csapo, Staff, Commander Naval Surface Forces
|Printer friendly Cite/link Email Feedback|
|Title Annotation:||FOCUS; damage-control|
|Date:||Sep 22, 2009|
|Previous Article:||Summer safety in the workplace.|
|Next Article:||ORM: the way to control risks of confined spaces.|