Physics Division

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Introduction

Reference Material

Policy and Requirements

Methods of Compliance

Operational Requirements

Appendices

1.

Properties of Liquids

2.

Relief Valve Sizing

2a.

Convective Heat Transfer

2b.

Relief Vent Pressure Drops

3.

Oxygen Deficiency Hazards

3.      PHYSICS DIVISION CRYOGENIC SAFETY POLICY AND REQUIREMENTS

In providing for cryogenic safety, hazards shall be considered as belonging to one of two classes:

1.           Hazards with a potential for personal injury.

         2.     Hazards that pose a risk to equipment and/or operation which have no potential for personal injury.

Hazards of the first class shall be reduced to as low a level as is reasonably achievable.  Hazards of the second class shall be reduced to as low a level as is cost-effective.

The existing DOE Order concerning cryogenic safety is Order 6430.1A Section 1574, which is primarily directed to liquefaction plants.  This Order nonetheless applies to all cryogenic systems, including those discussed here.  Section 1574 distinguishes two types of systems, namely, cryogenic storage vessels and cryogenic piping and fittings, with somewhat different rules and regulations for each class.

Some cryogenic experimental apparatus does not obviously fall into one class or the other.  To clarify this situation, Physics Division policy in applying DOE Order 6430.1A shall be the following:

         If a system involves the flow of cryogenic fluids through piping or subsystems contained in a vacuum chamber or vessel, the system shall be considered as a cryogenic storage vessel if the total volume of cryogenic fluid exceeds 12% of the volume of the surrounding vacuum vessel (even if the function of the apparatus is not cryogenic storage).  If the cryogenic fluid volume is less than this amount, the system may be considered to be cryogenic piping and fittings.

3.1    Policy for New Cryogenic Equipment and Systems

The Physics Division policy is that new equipment and systems shall:

1.       Meet all applicable federal and state requirements.

2.       Be as safe as practicable.

3.2    Policy for Existing Equipment and Systems

It should be noted that for existing systems, the applicable federal and state requirements are, in many instances, those that existed at the time of procurement or construction of the system in question.  The Physics Division policy for existing equipment and systems is that:

1.      Existing equipment and systems shall meet all applicable federal and state requirements.

2.      Existing equipment and systems must be as safe as practicable.

         3.   Existing equipment and systems shall be brought into compliance with current standards as far as is practicable.  Safety aspects of any exception to current standards shall be reviewed in detail, and further operation shall be contingent on approval by the Division Director.

3.3    Physics Division Cryogenic Safety Analysis and Review Requirements

To insure and document compliance with division policy, all cryogenic equipment and systems shall be subject to a safety review by the Cryogenic Safety Committee.

3.3.1 Documentation Required for Safety Review

 

The following documents are required for a safety review of cryogenic equipment or systems:

1.    A description of the system, which shall include the following:

A.     Schematics and flow diagrams as required to provide a complete and accurate functional description of the system.

B.     Sufficient information to show that the components, materials, and construction techniques used are appropriate.

C.     Parts lists with manufacturer�s specifications as appropriate; e.g. pressure ratings for vessels and plumbing, flow capacity and cracking pressure for relief valves, etc.

         D.   Specification of other, connected systems as may be required for safety analysis.

2.    A description of operating procedures, and of any necessary operator training.  The following elements shall be included:

A.     A list of all valves and ports which have the potential of discharging cold gas or cryogens to atmosphere (The possibility of such a discharge causing personal injury should be evaluated).

B.     All required system maintenance in any way impacting safety shall be detailed (e.g. periodic inspection of pressure relief devices).

         C.    Emergency procedures, including methods of evaluating and mitigating any oxygen deficiency hazard.

3.    A safety analysis detailing the consequences of all significant possible component failures or operator errors.  This shall include:

A.     A listing of all hazards and the steps taken to mitigate them.

B.      An analysis demonstrating the adequacy of pressure relief valve sizing under worst-case failure conditions.

         C.   Oxygen deficiency hazard (ODH) analysis evaluating the class of risk presented under worst-case failure conditions.  Any level of risk higher than Class 0 (refer to Appendix 3) requires that special precaution (refer to Appendix 3 also) will be necessary.