Monday, December 19, 2011

PIPE HANGERS AND SUPPORTS

PIPE HANGERS AND SUPPORTS - SELECTION AND APPLICATION Series 1


1. SCOPE

1.1 This Standard Practice presents the recommended practice for the selection and application of pipe hangers and supports for all service temperatures. 


2. OBJECTIVE

2.1 To serve as a pipe hanger and support specification for selection and application, by being referenced in whole or in part.

2.2 To serve as a guide to proven industry practice during engineering design and writing of job specifications covering the hanging, supporting and controlling the movement of piping systems.

2.3 To provide the erector with information on types of hanger and support components to be used for specific application and installations, where such information is not otherwise provided.

2.4 To serve as a companion document to MSS SP-58 which provides recommendations for material,  design and manufacture of standard types of pipe hanger components.

2.5 To serve as a companion document to MSS SP-89 which provides recommendations for fabrication and installation of pipe hangers and supports.

2.6 To serve as a companion document to MSS SP-127 which provides recommendations for the design,
selection, and application of bracing for piping systems subject to seismic - wind - dynamic loading.

3. CLASSIFICATION OF PIPING SYSTEMS

For the purpose of pipe hanger and support selection, this Standard Practice establishes an identification of piping systems according to the operating (service) temperatures of the piping contents as follows:

3.1 Hot Systems
      A-I. 120 °F (49 °C) to 450 °F (232 °C)
      A-2. 451 °F (233 °C) to 750 °F (399 °C)
      A-3. Over 750 °F (399°C)

3.2 Ambient Systems
      B. 60°F (16°C) to 119°F (48°C)

3.3 Cold Systems
       C-I. 33 °F (1 °C) to 59 °F (15 °C)
       C-2. -19 °F (-28 °C) to 32 °F (0 °C)
       C-3. -39 °F (-39 °C) to -20 °F (-29 °C)
       C-4. -40 °F (-40 °C) and below (Cryogenic Range)

4. GENERAL REQUIREMENTS

4.1 Where applicable, selection and application of pipe hangers and supports may be required to conform
to Codes and Standards, such as:
      - ASME B3 1 Codes for Pressure Piping
      - ASME Boiler and Pressure Vessel Codes
      - UL 203 Standard for Pipe Hanger Equipment for Fire Protection Service
      - Factory Mutual FM1951/1952/195 Approval Standard for Pipe Hanger Components for Automatic 
         Sprinkler Systems
      - NFPA 13
      - National and Local Building Codes
      - All other Applicable Codes

4.2 The selection of pipe hangers and supports shall be based upon the overall design concept of the piping systems and any special requirements which may be called for in the specifications. The supporting systems shall provide for, and control, the free or intended movement of the piping including its movement in relation to that of connected equipment.

4.3 A careful study shall be made of the piping layout in relation to the surrounding structure and adjacent piping and equipment before selecting the type of support to be used at each hanger point.

4.4 Hangers, supports, anchors and restraints shall be selected to withstand all static and specified dynamic conditions of loading to which the piping and associated equipment may be subjected.

4.5 When pipe hanger load and movement calculations are required by the design specification, the following must be considered:

a) Deadweight loads
b) Hydrostatic loads
c) Thermal loads
d) Loading due to expansion joint reaction forces

4.6 When occasional pipe hanger load calculations are required, they must be clearly defined in the design specification. Types of occasional loads are:

a) Safety valve thrust loads
b) Seismic loads
c) Wind, snow or ice loads
d) Turbine trip-out loads
e) Water hammer loads

4.7 Allowable stress levels listed in MSS SP-58 shall be used in the design of hanger assemblies with the following exceptions:

a) The load capacities for threaded hanger rods shall conform to Table 3 and Table A3 of MSS SP-58.

b) A 20% increase in allowable stress may be permitted for short time overloading conditions during operation.

c) For steels of known physical properties, an increase to 80% of minimum yield strength, at room temperature, during hydrostatic testing, is permissible. For steels of unknown physical properties, an increase to 80% of yield strength is permissible, as established by tensile testing a sample of material in accordance with ASTM A 370. The stress so established shall not exceed 19,000 psi (I 3 1 MPa).

d) Loading combination considerations and allowable stress levels to be applied shall be established by the Piping Design Engineer.

4.8 Hanger and support components shall be selected from Table 1 within the system classification. 

4.9 Where additional structural framing members are required, they shall be designed for the specific loads they are to support in accordance with the AISC Manual of Steel Construction - Allowable Stress Design, 9th Edition. No increase in allowable stress is permitted for hydrostatic test periods.

4.10 Hangers for the suspension of size 2'12 and larger pipe and tubing shall be capable of vertical hanger component adjustment under load.

         4.11 Building structure shall be adequate for supporting pipe hanger loads as generated in 4.5 and 4.6,
                 including hydrostatic test loads. In general, the Civil Design Engineer has this responsibility.

         4.12 Installed hangers or hanger Components shall be used only for their purpose. They shall not be 
                 used for rigging and erection purposes.

         4.13 Pipes shall not be suspended directly from each other unless formal calculations are performed
                 and accepted by the responsible Piping Design Engineer. If no calculations have been made, the
                 individual hanger for each horizontal pipe in a vertical bank shall have the load transmitted directly
                 to the rods, not the pipe above. Care shall be taken to size the rod appropriately for the total 
                 load at the support point.

5. MATERLAL REQUIREMENTS
 
5.1 The materials of all pipe hanging and supporting elements shall be in accordance with MSS SP-58.

5.2 The material in contact with the pipe shall be compatible with the piping material so that neither shall have a deteriorating action on the other.

5.3 Materials subject to corrosion or electrolysis shall be protected as specified by the engineering design and such protection shall be applied in accordance with the requirements of MSS SP-58. 

6. DIMENSIONAL REQUIREMENTS

6.1 Hangers and supports shall be sized to fit the outside diameter of pipe, tubing, or, if specified, the outside diameter of insulation. Manufacturers' catalog hangers provide a nominal clearance over standard molerance piping and tubing. Consideration for fit should be given by the user for large diameter and/or out of tolerance piping and tubing.

6.2 Dimensional tolerances shall be in accordance with Section 4 of MSS SP-89.
TABLE 1 - Hanger & Support Selections
(For Spring Hangers, See Table 2)
 
To find recommended hanger or support components,
I. Locate the system temperature and insulation condition in the two columns at left.
2. Read across the column beadings for the type of component to be used.
3. Numbers in boxes refer to those types shown in Figure 1, which corresponds to Figure 1 of MSS SP-58.


TABLE 1 - Hanger & Support Selections (Continued)
(For Spring Hangers, See Table 2)

 
NOTES:
1. Hangers on insulated systems shall incorporate protection saddles, shields, pipe clamps or welded lugs which project tbrongb the insulation to provide
2. The selection of type atid material shall be made by the Piping Design Engineer.
3. The design shall be in accordance with MSS SP-58 or as specified by the Piping Design Engineer.
4. For shields used with rollers or subject to point loading, see Table 5.
5. Continuous inserts, embedded plates, anchor bolts and concrete fasteners may be used ns specified by the Piping Design Engineer.
6. The need to maintain a vapor barrier may be required because of ambient dew point coosideratioos.






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