MTA-MA-031

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Administrative Items
Date	2/1/2025
Functional Area Where Benefits Will Be Realized	Maintenance and Engineering
Reference Implementation Guidance	Welding and Repair Technology Center: Implementation Guide for Use of Proprietary Sleeve Coupled Fittings (EPRI 3002023828) Common Design Package Content for a Non-Welded Fitting Installation in Non-Safety Related ASME B31.1 Piping Systems (EPRI 3002018349) Common Design Package Content for a Non-Welded Fitting Installation in ASME Safety-Related Piping Systems (EPRI 3002020835) Welding and Repair Technology Center: Evaluation of Small-Bore Mechanical Fittings: High-Cycle Fatigue Testing (EPRI 3002021068) Structural Integrity Testing of Small Bore Mechanical Pipe Fittings: Tensile and Torsion Testing of Low Alloy Steel Couplings (EPRI 3002020804) Flow-Accelerated Corrosion Evaluation of Non-Welded Pipe Fittings: Laboratory Testing of Carbon Steel and Low Alloy Steel Elbows (EPRI 3002026356)
Industry SME	EPRI PRR Contact: NuclearPlantMod@epri.com
Previous Implementation	This methodology has been implemented at several nuclear plants. Please contact the EPRI SME for additional information.
Implementation Enablers	N/A
Applicability	All reactor types All geographic regions
Keywords	FAC; Non-welded fittings; Lokring fittings; small-bore pipe fitting; socket-welded fittings; common design package; standard design process; ASME B31.1; ASME Section III; high-cycle fatigue; mechanical fitting; proprietary sleeve coupled fitting; safety-related; non-safety related; flanged fittings; butt-welded fittings; Class 1; Class 2; Class 3
Business Case Analysis Cross-Reference	N/A

Description

The need to repair piping is universal across the nuclear power industry. Non-welded fittings are compression‑type mechanical fittings that connect tubing and piping with no welding, enabling quick tubing and piping repairs. The use of them replaces flanged, butt‑welded and socket‑welded fittings and reduces installation time, cost, radiation exposure, and potentially outage critical path.

Testing of sample fittings has shown this fitting design can be qualified to meet ASME NQA‑1 Code requirements and US NRC 10 CFR 50 Appendix B program requirements utilizing the commercial‑grade dedication process. Specifically, they meet testing and design requirements for ASME Section III, B16.9 and B31.1. As such these fittings can be used for Limited Class 1, Class 2 and Class 3 piping systems in both safety and non‑safety related applications.

A US nuclear utility enlisted EPRI’s assistance in testing the fittings and developing a common design package to help standardize the design modification process for fleet‑level and site‑specific installations. This enables improved sharing of operating experience and the potential for reducing individual site costs for developing design change packages for non‑welded fitting installation.

Transitioning from welded piping to mechanical fittings has been demonstrated to result in cost savings from reduced installation labor and reduced worker radiation exposure. The cost savings are maximized in applications with the highest area dose rates and largest pipe sizes. Savings in non‑safety related applications are still realizable in low‑dose fields.

Benefits

Benefits Estimate

Level 1 – Savings are less than $1 million per year. The savings are primarily in the reduced labor and associated personnel dose during installation. One job can save hundreds of thousands of dollars.

Benefits Description

• Quality and safety are maintained by use of mechanical fittings as an alternative to welded fittings, reducing labor cost, installation time and worker dose.
• Non‑welded fittings are acceptable to existing design standards such as ASME Section III, B16.9 and B31.1.
• Reduced welding resources required during outages and on‑line installations; a key advantage of mechanical fitting is that their installation does not require skilled labor even in challenging locations.
• Quick safety‑related repairs can be made during unplanned outages or in response to emergent outage inspection findings.
• An extensive amount of testing has demonstrated that the high-cycle fatigue non-welded fittings perform equal to socket-welded fittings in high-vibration environment.

Costs and Schedule

Cost

Level 3 – Implementation cost is less than $1 million. For non‑safety fittings the costs are primarily in preparation of the engineering change package, procurement of tooling and fittings, and personnel training. For safety‑related fittings the costs are primarily in fitting design qualification, testing surveillance, procurement and commercial‑grade dedication, and engineering change package development. EPRI research has provided the technical justification for qualification of the fittings as well as a common design package that site personnel can use in their design modification process.

Schedule

	Non Safety-Related	Safety-Related
Engineering Change Package Preparation (hrs)	60-80 (N/A with updated piping design specification)	180-240
Design Qualification	N/A	240-280
Procurement (hrs)	16	283
Training (hrs)	165	165
Installation (hrs/fitting)	<1	<1

Scope Context

Cost and savings are based on implementation at several US nuclear sites.

Risks

• Sites should consider and evaluate all site-specific regulatory commitments and deviations from the Codes, standards and materials used in the Common Design Package (CDP) and testing reports.
• Improper installation is the main cause of failure of these non-welded fittings. Sites should ensure adequate installation documents, personnel training, hold points and procedural compliance.
• Clearance requirements for the installation tool will vary depending on the size of the associated fitting to be installed. Ensure adequate clearance is available in the field for the installation process and tooling.
• Some stainless-steel fittings have experienced chloride-induced, stress corrosion cracking of external surfaces of the fittings driver ring in marine applications. Care should be taken to ensure proper materials are selected where known environmental conditions, coupled with high residual stresses potentially results in material degradation.

SWEEP Score

Category	Level	Description
Cost	3	Implementation cost is less than $1 million (inclusive).
Savings	1	Savings are less than $1 million per year (inclusive).
Payback (Safety Related)	2	Payback period is greater than one year but less than five years (inclusive).
Payback (Non-Safety Related)	3	Payback period is less than one year (inclusive).
Licensing Readiness (Safety Related)	2	Regulatory guidance changes are recommended for implementation (ASME Section III plants – up to 2 in., B31.1 plants – no guidance changes required).
Licensing Readiness (Non-Safety Related)	3	No changes are required for implementation.
Technology Readiness	3	The technology is ready for wide operational deployment.
Implementation Proficiency	3	The technology can be implemented by all sites, regardless of digital experience.