ASME PCC-2 Overview Episode 6 (Article 501: Pressure and Tightness of Piping and Equipment)

Introduction to Pressure Equipment Integrity Testing

Overview of Athabasca Engineering Solutions

• Chris Kurzick introduces himself as the principal engineer at Athabasca Engineering Solutions (AES), which specializes in third-party value evaluations, training and certification, and equipment re-rating.

Progress in PCC Two

• The discussion continues from previous episodes, focusing on pressure tightness of piping and equipment. The episode covers articles related to pressure equipment integrity testing after alterations or repairs.

Understanding Article 501: Pressure Equipment Integrity Testing

Purpose of Article 501

• Article 501 focuses on pressure equipment integrity testing following alterations or repairs, applicable to tubular heat exchangers, pressure vessels, and piping.

Types of Tests Covered

• The article outlines various testing methods including hydrostatic testing, pneumatic testing, and non-destructive examination (NDE). It emphasizes determining the appropriate test type based on specific criteria.

Key Definitions in Pressure Testing

Important Terms Explained

• A closure weld is defined as the final weld connecting piping components. Hydrostatic tests involve liquid pressure tests typically using water for tightness verification.

• In-service tests are leak tests performed at startup without reaching full pressure. Pneumatic tests utilize gas (usually air or nitrogen).

When is Pressure Testing Required?

Conditions Necessitating Pressure Testing

• Pressure testing is mandated when there are alterations to the pressure envelope or repairs that affect its integrity. Re-rating due to increased temperature also requires testing unless within design limits.

Example Scenario for Testing Procedures

Decision-Making Process for Testing

• An example illustrates how to determine if an alteration report is needed by assessing whether structural integrity certification is required after damage or repair.

• If structural integrity checks out post-repair, a decision must be made regarding acceptable leak test methods based on service safety considerations.

Brittle Fracture Considerations

Evaluating Risks During Testing

• It's crucial to check for brittle fracture risks during fitness-for-service evaluations. Tests should be conducted at least 17°C above the minimum design metal temperature (MDMT).

Final Steps in Evaluation Process

Addressing Mechanical Stress Relief

• If initial criteria aren't met for safe operation, mechanical stress relief may resolve issues before proceeding with further evaluation against welding codes.

Preferred Methods of Pressure Testing

Liquid vs. Gas Pressure Testing

Hydrostatic vs. Pneumatic Testing: Key Considerations

Understanding Stored Energy and Safety Precautions

• The discussion emphasizes the importance of being cautious with stored energy, particularly in incompressible fluids, which can pose significant risks if not handled properly.

• When considering pneumatic testing or non-destructive evaluation (NDE), it's crucial to assess whether the hydrostatic fluid weight could compromise the existing structure.

• Potential issues include process contamination from water used in tests, which may affect internal linings and sensitive instruments due to corrosion products.

Temperature and Material Concerns

• High temperatures during in-service pressure testing can lead to material boiling off, necessitating alternative methods such as gas testing for safety reasons.

• Alternatives like pneumatic testing or NDE are highlighted as options when traditional hydrostatic methods are unsuitable.

Decision-Making Criteria for Testing Methods

• A critical decision point involves determining if equipment can safely support hydrotest loads; structural integrity is paramount to avoid potential failures.

• Contamination by liquids is a recurring concern that must be addressed before proceeding with hydrostatic tests or localized pressure tests.

Risk Assessment and Alternative Strategies

• If structural reinforcement is too costly or impractical, other strategies must be considered, including localized hydro tests as alternatives to full-scale hydrostatic tests.