ASME B31.3 Process Piping - Designing with Expansion Joints

ASME B31.3 Process Piping - Designing with Expansion Joints

Designing with Expansion Joints

• Types of Expansion Joints
• Pressure Thrust
• Installation of Expansion Joints
• Metal Bellows Expansion Joints

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ASME B31.3 Process Piping - Reactions

ASME B31.3 Process Piping - Reactions

• General Considerations
• Fabricated Equipment
• Rotating Equipment
• Supports
• Cold Spring

General Considerations

• Main purpose is to provide sufficient support and flexibility to prevent the piping from exerting excessive reactions on equipment and restraints
• The calculation methods are different for fabricated equipment than for rotating equipment or supports
• Reaction limits are determined differently for fabricated equipment than for rotating equipment or supports

Fabricated Equipment

• Calculation Methods
• Reaction Limits
• Nozzle Flexibility

Calculation Methods

• Usually the accuracy of a formal analysis using a computer stress analysis program is required
• Both sustained loads and displacement loads are considered
• Failure modes for fabricated equipment include:

• Gross deformation or collapse

• Fatigue

• In order to evaluate fatigue, the entire range of loads must be considered, so the temperature range for this calculation is the same as for calculating the displacement stress range

FOR MORE INFO, SEE THE EMBEDDED PDF. GIVE IT A MINUTE TO LOAD.

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ASME B31.3 Process Piping - Flexibility and Stress

ASME B31.3 Process Piping - Flexibility and Stress

• General Considerations
• Friction
• Stress Intensification
• Thermal Expansion
• Spring Hangers
• The Displacement Load Analysis

General Considerations

• Main purpose is to provide sufficient flexibility to safely accommodate changes in length resulting from temperature variations, avoiding failure caused by
• Fatigue
• Creep-fatigue
• Ratchet
• Another purpose is to keep movement of piping within a manageable range
• Avoiding interference with other stuff
• Supports designed to handle displacements

General Considerations

• Loads are actions that cause one end of a pipe segment to move relative to the other end and actions that have an equivalent effect
• Thermal expansion of attached equipment
• Temperature changes in the piping
• Peak stresses are accounted for using stress intensification factors
• Acceptance criterion is based on the stress range

Friction

• Displacement causes piping to move over sliding supports
• Friction forces are in one direction when the pipe is heating and in the opposite direction when cooling
• The coefficient of friction used for steel on steel ranges from 0.3 to 0.5.

FOR MORE INFO, SEE THE EMBEDDED PDF. GIVE IT A MINUTE TO LOAD.

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ASME B31.3 Process Piping - Layout and Support

ASME B31.3 Process Piping - Layout and Support

General Considerations

• Access for operation (valves)
• Access for maintenance of in-line devices

• instrumentation

• Traps

• strainers, etc.

• Avoiding interference with other activities

• Removing heat exchanger bundles

• Clearance for pump maintenance, etc.

• Appearance
• Drainage (slope) requirements
• Pressure drop
• Cost of piping, including maximizing use of existing supports
• Avoiding interference with other piping

• Clearance for application of insulation

• Clearance for piping displacement, etc.

• Provisions for future additions

Support Spacing

Two principal sources:

1. Recognized codes & standards

• ASME B31.1
• MSS SP-69: Pipe Hangers and Supports – Selection and Application

2. Owner or designer calculated values

Usually based on simplifying assumptions

• Combination of pipe material and wall thickness used in the facility that gives the shortest spans
• Contents specific gravity, usually 1.0
• Typical insulation thickness and density
• Person walking on pipe for larger sizes

FOR MORE INFO, SEE THE EMBEDDED PDF. GIVE IT A MINUTE TO LOAD.

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ASME B31.3 Process Piping - Perform flexibility Analysis

ASME B31.3 Process Piping - Perform flexibility Analysis

What are we trying to achieve?

1. Provide adequate support to resist loads suc h as pressure, weight, earthquake and wind

2. Provide sufficient flexibility to safely accommodate changes in length resulting from temperature variations

3. Provide sufficient support and flexibility to prevent the piping from exerting excessive reactions on equipment and restraints

And we do that in order to

• make the piping look well supported to the facility engineers and operators
• prevent collapse of the piping
• prevent leaks due to fatigue cracks
• prevent joint leakage caused by excessive forces , and
• prevent failure or malfunction of attached equipment caused by excessive reactions

Flexibility Analysis Example

A two step analysis is shown.
1. Weight and Pressure Loads – verify proper support and check reactions
2. Thermal Expansion Load – verify adequate flexibility and check reactions

FOR MORE INFO, SEE THE EMBEDDED PDF. GIVE IT A MINUTE TO LOAD.

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ASME B31.3 Process Piping - Valve Selection

Valve Selection

• Code Requirements
• Selection by Valve Type

• Gate

• Globe

• Check

• Butterfly

• Ball

• Plug

Code Requirements

Listed Valves

• Can be used within their pressure-temperature ratings and any additional limitations described in the Code
• Except that bolted bonnets secured by fewer than 4 bolts or a U-bolt may only be used in Category D Fluid Service.

Unlisted Valves can be used within Code limitations

if they:

• have dimensions that “conform to those of comparable listed components insofar as practicable”
• “provide strength and performance equivalent to standard components”, and satisfy one of the following:
• pressure-temperature ratings established by the method described in Annex F of ASME B16.34, or are qualified for pressure design as required by para. 304.7.2.

Selection by Valve Type

• Gate
• Globe
• Check
• Butterfly
• Ball
• Plug

FOR MORE INFO, SEE THE EMBEDDED PDF. GIVE IT A MINUTE TO LOAD.

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ASME B31.3 Process Piping - Pressure Design of Metals

Pressure Design of Metals

• Design Pressure & Temperature
• Quality Factors
• Weld Joint Strength Factor
• Pressure Design of Components

• Four Methods

• Straight Pipe

• Fittings

• Fabricated Branch Connections

• Flanges and Blanks

• Other Components

• Piping Material Specifications

Design Pressure & Temperature

design pressure: the pressure at the most severe condition of internal or external pressure and temperature expected during service (301.2)

• The most severe condition is that which results in the greatest required component thickness and the highest component rating.
• The inside pipe in jacketed piping shall be designed for the most severe combination of conditions expected during service.
• Short-term variations may be considered separately. (302.2.4)

Provisions shall be made to safely contain or relieve any pressure to which the piping may be subjected.

Sources of pressure to be considered include:

• Ambient influences
• Pressure oscillations
• Improper operation
• Decomposition of fluids
• Static head
• Failure of control devices

FOR MORE INFO, SEE THE EMBEDDED PDF. GIVE IT A MINUTE TO LOAD.

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ASME B31.3 Process Piping - Fine Tune Piping Material Decisions

Materials

• Strength of Materials
• Bases for Design Stresses
• B31.3 Material Requirements

• Listed and Unlisted Materials

• Temperature Limits

• Toughness Requirements

• Deterioration in Service 

The Material in This Section is Addressed by B31.3 in:

• Chapter II - Design
• Chapter III - Materials
• Appendix A - Allowable Stresses & Quality
• Factors – Metals
• Appendix F - Precautionary Considerations

Strength of Materials

• Stress
• Strain
• Stress-Strain Diagram

• Elastic Modulus

• Yield Strength

• Ultimate Strength

• Creep
• Fatigue
• Brittle versus Ductile Behavior

Fatigue failure: A failure which results from a repetitive load lower than that required to cause failure on a single application

Bases for Design Stresses

Most Materials – (materials other than gray iron, malleable iron and bolting) below the creep range, the lowest of (302.3.2)

• 1/3 of specified minimum tensile strength (ST)
• 1/3 of tensile strength at temperature
• 2/3 of specified minimum yield strength (SY)
• 2/3 of yield strength at temperature; except for austenitic stainless steels and nickel alloys with similar behavior, 90% of yield strength at temperature

FOR MORE INFO, SEE THE EMBEDDED PDF. GIVE IT A MINUTE TO LOAD.

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ASME B31.3 Process Piping - Metallic Pipe & Fitting Selection

Piping Development Process

1. Establish applicable system standard(s)
2. Establish design conditions
3. Make overall piping material decisions

• 􀂃 Pressure Class
• 􀂃 Reliability
• 􀂃 Materials of construction

4. Fine tune piping material decisions

• 􀂃 Materials
• 􀂃 Determine wall thicknesses
• 􀂃 Valves

5. Establish preliminary piping system layout & support configuration
6. Perform flexibility analysis
7. Finalize layout and bill of materials
8. Fabricate and install
9. Examine and test

Metallic Pipe & Fitting Selection

• Piping System Failure
• Bases for Selection
• Listed versus Unlisted Piping Components
• Fluid Service Requirements
• Pipe
• Fittings
• Branch Connections
• Flanges
• Gaskets
• Bolting
• Flanged Joints

Piping System Failure

How can you recognize a failure in a piping system?

Bases for Selection

Pressure Class
Reliability

• 􀂃 Robustness
• 􀂃 Fire Resistance
• 􀂃 Blow-out Resistance
• 􀂃 Tendencies to leak

Material of Construction

• 􀂃 Corrosion Resistance
• 􀂃 Material Toughness

Cost

Pressure Class

Ratings for above ground metallic systems are generally governed by their joints. Frequently these are flanged joints manufactured in accordance with ASME B16.1 (iron flanges) and ASME B16.5 (other metallic flanges).

Ratings for flanges (and some other piping components) are designated by pressure class.

FOR MORE INFO, SEE THE EMBEDDED PDF. GIVE IT A MINUTE TO LOAD.

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ASME B31.3 Process Piping Course - Introduction

Scope of B31.3 Course

This course covers piping as typically used in process plants

Not covered:

• 􀂃Pipelines
• 􀂃Plumbing
• 􀂃Nuclear plant piping

Topics Covered

1. Introduction

2. Metallic Pipe & Fitting Selection
3. Materials
4. Pressure Design
5. Valve Selection
6. Flexibility Analysis
7. Layout and Support
8. Flexibility
9. Support and Equipment Load Limits
10. Flexibility Analysis Methods

11. Designing with Expansion Joints

12. Fabrication and Installation

13. Inspection, Examination and Testing

14. Category M Fluid Service

15. Nonmetallic Piping Systems

16. High Pressure Piping

17. Inspection, Repair, Alteration and Rerating

18. What’s Different in B31.1

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