Thin Walled Corrosion Resistant Steel (CRES) Pipe Inspections
Navy SBIR 2014.1 - Topic N141-051
NAVSEA - Mr. Dean Putnam -
Opens: Dec 20, 2013 - Closes: Jan 22, 2014

N141-051 TITLE: Thin Walled Corrosion Resistant Steel (CRES) Pipe Inspections

TECHNOLOGY AREAS: Materials/Processes

ACQUISITION PROGRAM: PMS 312 In-Service Aircraft Program Office, PMS 378/379 Future Aircraft Car

OBJECTIVE: The objective is to develop an innovative technology that inspects thin walled CRES welded joints within Jet Propulsion Grade JP-5 fuel lines.

DESCRIPTION: Thin walled (Schedule 10) CRES 316L pipe (ref. 1) has been used in JP-5 fuel systems (ref. 2). The pipe joint design uses a belled end fitting creating an inherent crevice. The thinness of this piping may lead to poor weld quality at the welded joints which could cause additional crevices within the pipe joint. Crevices create areas for corrosion to form eventually resulting in leakage across the pipe joints. This type of pipe is currently in use and there is a need to create an easily applied method to non-destructively inspect welded joints to identify areas where repair work may be necessary to preclude possible leakage. In many instances, there is limited access space surrounding the pipe joint.

Pipe joint leakage failures were identified on the Aircraft Carrier USS George H.W. Bush (CVN 77) within the first three years of service. The JP-5 fuel system installed on CVN 77 and planned for all FORD Class Carriers have over 28,000 welded joints per ship. Additional failures are expected to be identified.

Any material or technique developed must be safe for use in fuel piping and applicable for pipe sizes ranging from 2 to 12 inches. Joint types include couplings, tees and elbows which may be made using sockets or belled end fittings. Currently available non-destructive inspections for pipe interiors are too expensive and cumbersome to be applied on a wide scale for In-Service Carriers. Due to pipe lengths and configurations, current visual test inspections have not proven reliable. Therefore, a low cost method to non-destructively measure wall thickness and determine internal pipe weld quality is needed to ensure safe and efficient JP-5 system operation. Replacing all thin walled welded joints or non-destructively testing all welded joints with currently available testing techniques are both impractical and too expensive.

The new thin walled CRES pipe inspection technique shall be safe to use with fuel piping and achieve competing objectives of low cost, ease of inspection, and accurate identification of areas of potential leakage in the thin walled pipe joints. Current Radiographic Testing (RT) approaches are expensive, cumbersome, require greater access to pipe location than is often available, and have many environmental restrictions and require the use of trained technicians on their use. Ref. 3 (pages 5 through 10) identifies an American Society of Mechanical Engineers (ASME) Code Case discussion regarding "Use of Ultrasonic Examination of Welds as an Alternative to Radiographic Examination ASME B31.3, Chapter IX". Due to the size of the components, current RT systems require several inches of access around the pipe. In addition, highly restrictive access is required due to the presence of radiological components. Recent advances in Ultrasonic Testing (UT) and Automated Ultrasonic Testing (AUT) (ref. 4 and 5) have been primarily focused on large pipes (>12 inches), require specialized development for specific materials and applications, and have similar cost and pipe access requirements as RT. An innovation to existing technologies or development of new approaches is needed to address these shortfalls while delivering equal or better test results.

PHASE I: The company will develop a concept for an inexpensive and easily performed non-destructive inspection method to use on thin walled CRES pipe joints. The concept should demonstrate how the non-destructive method could be performed with limited access to the pipe joint, and should present reasonable cost estimates. Feasibility will be established by material testing and/or through analytical modeling. The small business will provide a Phase II development plan that addresses technical risk reduction and provide performance goals and key technical milestones.

PHASE II: Based on the results of Phase I and the Phase II development plan, the small business will develop a prototype for evaluation. The prototype will be evaluated to determine its capability in meeting the performance goals defined in the Phase II development plan and the Navy requirements for the thin walled CRES pipe joint non-destructive method. The non-destructive inspection device and method performance will be demonstrated through prototype evaluation and testing over the required range of parameters including numerous deployment cycles and destructive testing to verify non-destructive test results. Evaluation results will be used to refine the prototype into an initial design that will meet Navy requirements. The company will prepare a Phase III development plan to transition the technology for Navy use.

PHASE III: The company will be expected to support the Navy in transitioning the technology for Navy use. The company will develop a thin walled CRES pipe joint non-destructive inspection device and/or method according to the Phase III development plan for evaluation to determine its effectiveness in an operationally relevant environment. The company will support the Navy for test and validation to certify and qualify the system for Navy use.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: If successfully demonstrated, there may be a commercial market for this thin walled pipe joint non-destructive inspection method in any industry that employs thin walled CRES piping such as petroleum production or distribution.

1. "Pipe and Tubing, Carbon, Alloy, and Stainless Steel, Seamless and Welded, Military Specification Mil-P-24691 Grade 316L", 23 September 1987,

2. "Turbine Fuel, Aviation Grades JP-4 and JP-5, Military Specification Mil-DTL-5624U", 18 September 1998,

3. "Use of Ultrasonic Examination of Welds as an Alternative to Radiographic Examination is ASME B31.3, Chapter IX", American Society of Mechanical Engineers B31 Standards Committee, January 4, 2012

4. Michael Moles and Ed Ginzel, "Phased Array for Small Diameter, Thin-Walled Piping Inspections", 18th World Conference on Nondestructive Testing, 16-20 April 2012.

5. Roger Spencer , "Advanced Technologies and Methodology for Automated Ultrasonic Testing Systems Quantification", Edison Welding Institute, February 15, 2013

KEYWORDS: Thin walled CRES; inspection of welded joints; non-destructive pipe inspections; leakage across pipe joints; low cost method to non-destructively inspect; non-destructive in-situ pipe inspection; JP-5 fuel

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