Safety Standard for Pressure Vessels for Human Occupancy

AN A MERICAN NA TIONAL S T AND ARD

ASME PVHO-1–2016

(Revision of ASME PVHO-1–2012)

ASME PVHO-1–2016

(Revision of ASME PVHO-1–2012)

Safety Standard for Pressure Vessels for Human Occupancy

AN AMERICAN NA TIONAL S T AND ARD

Two Park Avenue • New York, NY • 10016 USA

Date of Issuance: August 29, 2016

The next edition of this Standard is scheduled for publication in 2019.

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CONTENTS

Foreword vii

Committee Roster viii

Correspondence With the PVHO Committee x

Summary of Changes xii

Section 6 Diving Systems 101

1. General 101

2. Design 102

3. Pressure Boundary 104

4. Systems 105

5. Testing 110

6. Quick-Acting Closures for Diving Bells and Emergency Evacuation

Systems 110

Section 7 Submersibles 112

1. General 112

2. Pressure Boundary 113

3. Piping 114

4. Electrical Systems 114

5. Life Support 115

6. Fire Protection 116

7. Navigation 116

8. Communications 117

9. Instrumentation 117

10. Buoyancy, Stability, Emergency Ascent, and Entanglement 117

11. Emergency Equipment 118

Figures

1-7.13.1-1 Geometry of Cylinders 7

1-7.13.1-2 Stiffener Geometry 8

1-7.13.1-3 Sections Through Rings 8

1-7.13.5-1 Values of t/Ro and Lc /Ro 12

1. Form of Nameplate, U.S. Customary 14

2. Form of Nameplate, Metric 14

2-2.2.1-1 Standard Window Geometries — Part 1 18

2-2.2.1-2 Standard Window Geometries — Part 2 19

2-2.2.1-3 Standard Window Geometries — Part 3 20

2-2.2.1-4 Standard Window Geometries — Part 4 21

2-2.5.1-1 Short-Term Critical Pressure of Flat Disk Acrylic Windows — Part 1 26

2-2.5.1-2 Short-Term Critical Pressure of Flat Disk Acrylic Windows — Part 2 27

2-2.5.1-3 Short-Term Critical Pressure of Flat Disk Acrylic Windows — Part 3 28

2-2.5.1-4 Short-Term Critical Pressure of Conical Frustum Acrylic Windows —

Part 1 29

2-2.5.1-5 Short-Term Critical Pressure of Conical Frustum Acrylic Windows —

Part 2 30

2-2.5.1-6 Short-Term Critical Pressure of Spherical Sector Acrylic Windows — Part

1 ....................................................................... 31

2-2.5.1-7 Short-Term Critical Pressure of Spherical Sector Acrylic Windows — Part

2 ....................................................................... 32

2-2.5.1-8 Short-Term Critical Pressure of Cylindrical Acrylic Windows Pressurized Internally — Part 1 34

2-2.5.1-9 Short-Term Critical Pressure of Cylindrical Acrylic Windows Pressurized Internally — Part 2 35

2-2.5.1-10 Short-Term Critical Pressure of Cylindrical Acrylic Windows Pressurized Externally 36

2-2.5.1-11 Short-Term Elastic Buckling of Cylindrical Acrylic Windows Between

Supports Under External Hydrostatic Pressure — Part 1 37

2-2.5.1-12 Short-Term Elastic Buckling of Cylindrical Acrylic Windows Between

Supports Under External Hydrostatic Pressure — Part 2 38

2-2.5.1-13 Short-Term Elastic Buckling of Cylindrical Acrylic Windows Between

Supports Under External Hydrostatic Pressure — Part 3 39

2-2.5.1-14 Short-Term Critical Pressure of Hyperhemispherical and NEMO-Type

Acrylic Windows — Part 1 40

2-2.5.1-15 Short-Term Critical Pressure of Hyperhemispherical and NEMO-Type

Acrylic Windows — Part 2 41

2-2.10.1-1 Seat Cavity Requirements — Conical Frustum Window, Spherical Sector

Window With Conical Edge, and Flat Disk Window 45

2-2.10.1-2 Seat Cavity Requirements — Double Beveled Disk Window 46

2-2.10.1-3 Seat Cavity Requirements — Spherical Sector Window With

Square Edge 47

2-2.10.1-4 Seat Cavity Requirements — Hemispherical Window With

Equatorial Flange 48

2-2.10.1-5 Seat Cavity Requirements — Cylindrical Window 49

2-2.10.1-6 Seat Cavity Requirements — Hyperhemispherical Window 50

2-2.10.1-7 Seat Cavity Requirements — NEMO Window (Standard Seat) 51

2-2.10.1-8 Seat Cavity Requirements — NEMO Window (Seat With Extended Cyclic

Fatigue Life) 52

2-2.11.10-1 Bevels on Window Edges — Flat Disk Windows, Conical Frustum

Windows, Spherical Sector Windows, Hyperhemispheres 54

2-2.11.10-2 Bevels on Window Edges — Flanged Hemispherical Window, Spherical Sector Window With Square Edge, External Pressure and Internal

Pressure of Cylindrical Windows 55

2-2.11.11-1 Acceptable Configurations for Clear Viewport Retaining Covers 57

2-2.14.11-1 Dimensional Tolerances for Penetrations in Acrylic Windows 61

2-2.14.15-1 Dimensional Tolerances for Inserts in Acrylic Windows 63

2-2.14.16-1 Typical Shapes of Inserts 64

2-2.14.22-1 Seal Configurations for Inserts in Acrylic Windows 66

2-2.14.24-1 Restraints for Inserts in Acrylic Windows 67

4-9.14.2-1 Flow Diagram of Apparatus for Measuring the Concentration of Hydrocarbons in a Stream of Air or Other Gas After It Has Passed

Through a Test Hose 98

6-4.5.2.2-1 Placement and Design of Markings of Hyperbaric Rescue Systems

Designed to Float in Water 109

6-4.5.2.2-2 Markings of Hyperbaric Rescue Systems Designed to Float in Water 109

Tables

1-10-1 Conversion Factor, Fp (for PVHO Occupation Exceeding 8 hr) 15

2-2.3.1-1 Conversion Factors for Acrylic Flat Disk Windows 23

2-2.3.1-2 Conversion Factors for Acrylic Conical Frustum Windows and Double

Beveled Disk Windows 23

2-2.3.1-3 Conversion Factors for Acrylic Spherical Sector Windows With Conical Edge, Hyperhemispherical Windows With Conical Edge, and NEMO-

Type Windows With Conical Edge 24

2-2.3.1-4 Conversion Factors for Acrylic Spherical Sector Windows With Square

Edge and Hemispherical Windows With Equatorial Flange 24

2-2.3.1-5 Conversion Factors for Acrylic Cylindrical Windows 25

2-2.3.2-1 Conical Frustum Windows for Design Pressures in Excess of 10,000 psi

(69 MPa) 25

2-2.14.13-1 Specified Values of Physical Properties for Polycarbonate Plastic 62

2-2.14.13-2 Specified Values of Physical Properties for Cast Nylon Plastic 62

2-3.4-1 Specified Values of Physical Properties for Each Lot 69

2-3.4-2 Specified Values of Physical Properties for Each Casting 71

2-4.5-1 Annealing Schedule for Acrylic Windows 75

4-2.1.1-1 Maximum Allowable Stress Values for Seamless Pipe and Tube Materials

Not Listed in Nonmandatory Appendix A of ASME B31.1 87

4-7.1-1 Mandatory Minimum Nondestructive Examinations for Pressure Welds

in Piping Systems for Pressure Vessels for Human Occupancy 92

4-9.14.2-1 Maximum Allowable Concentration of Hydrocarbons in Air Passing

Through Hose 98

Mandatory Appendices

1. Reference Codes, Standards, and Specifications 119

2. Definitions 121

Nonmandatory Appendices

1. Design of Supports and Lifting Attachments 127

2. Recommendations for the Design of Through-Pressure Boundary

   Penetrations 128

3. Recommended Practices for Color Coding and Labeling 131

4. Guidelines for the Submission of a PVHO Case for the Use of

   Nonstandard Designs, Materials, and Construction 132

5. Guidelines for Preparing a PVHO Performance-Based Case for Flexible

   Chambers 138

6. Useful References 153

FOREWORD

Early in 1971, an ad hoc committee was formed by action of the ASME Codes and Standards Policy Board to develop design rules for pressure vessels for human occupancy. The importance of this task was soon recognized, and the ASME Safety Code Committee on Pressure Vessels for Human Occupancy (PVHO) was established in 1974 to continue the work of the ad hoc committee. Initially, this committee was to confine its activity to the pressure boundary of such systems. It was to reference existing ASME Boiler and Pressure Vessel Code (BPVC) sections, insofar as practicable, adapting them for application to pressure vessels for human occupancy. The common practice hitherto had been to design such chambers in accordance with Section VIII, Division 1 of the ASME BPVC; however, a number of important considerations were not covered in those rules. Among these were requirements for viewports and the in-service use of pressure relief valves, and special material toughness requirements. This Standard provides the necessary rules to supplement that section, and also Section VIII, Division 2 of the BPVC. The user is expected to be familiar with the principles and application of the Code sections.

BPVC criteria furnish the baseline for design. In PVHO-1, design temperature is limited to 0°F to 150°F (−18°C to 66°C). Supporting structure and lifting loads are given special attention. Certain design details permitted by Section VIII are excluded. A major addition is the inclusion of design rules for acrylic viewports (Section 2). The formulation of rules for these vital and critical appurtenances was one of the reasons for establishing the PVHO Committee. Finally, all chambers designed for external pressure are required to be subjected to an external pressure hydrostatic test or pneumatic test.

The 2007 edition was completely rewritten and reformatted from the 2002 edition. Section 1, General Requirements, is intended to be used for all PVHOs, regardless of use. The rules for external pressure design were expanded to include unstiffened and ring-stiffened cylinders, in addition to spheres. Other additions included sections pertaining to application-specific PVHOs. Sections were included for medical hyperbaric systems, diving systems, submersibles, and quality assurance. The piping section was expanded. Where possible, Mandatory Appendices were incor- porated into the body of the document. All Forms were revised to reflect the document (PVHO-1), an abbreviation denoting the corresponding section (e.g., General Requirements is GR), and the form number within that Section. An example is PVHO-1 Form GR-1.

The 2012 edition included expansions made to the General Requirements, Viewports, and Diving Systems Sections.

The 2016 edition includes additional expansions made to the General Requirements, Viewports, Medical Hyperbaric Systems, and Diving Systems Sections. It includes a new Nonmandatory Appendix for preparing PVHO performance-based Cases for flexible chambers. There is continu- ing work being accomplished by the Subcommittees in the areas of PVHOs using nonstandard materials, including nonmetallic PVHOs. A companion document (PVHO-2) that covers in-service guidelines for PVHOs has been published.

The 2016 edition of PVHO-1 was approved and adopted by the American National Standards Institute as meeting the criteria as an American National Standard on January 20, 2016. Previous editions were published in 1977, 1981, 1984, 1987, 1993, 1997, 2002, 2007, and 2012.

ASME PRESSURE VESSELS

FOR HUMAN OCCUPANCY COMMITTEE

(The following is the roster of the Committee as of November 10, 2015.)

STANDARDS COMMITTEE OFFICERS

G. K. Wolfe, Chair

J. Witney, Vice Chair

G. E. Moino, Secretary