Page 156 - GRINNELL Mechanical Products Catalogue

pRESSuRE & DESiGN DATA
Rigid Joints
GRINNELL Rigid Couplings provide rigid gripping of the pipe . They are designed to bring the pipe ends close together and to ensure the coupling clamps firmly onto the pipe OD and the bottom of the grooves . Because rigid couplings clamp around the entire pipe surface, they provide resistance to flexural and torsional loads and therefore permit longer spacing to ASME/ANSI B31 .1 (Power Piping) and ASME/ANSI B39 .1 (Building Services) requirements .
Flexible Joints
GRINNELL Flexible Couplings act as an “expansion joint”, allowing linear
and angular movement of the pipe . They are designed with the coupling keys engaging the pipe without gripping on the bottom of the grooves, while still providing for a restrained mechanical joint . This is particularly useful to allow for pipe expansion/contraction and piping misalignment .
Tech Data Sheet: G820
Linear Movement (Flexible Couplings)
For design purposes, the maximum pipe end gap should be reduced to account for field practises as follows:
For thermal expansion with flexible couplings, the pipe ends at each
joint should be fully gapped to
the maximum amount . This can be accomplished by pressurising the system and then anchoring the system .
For thermal contraction with flexible couplings, the pipe ends at each joint should be fully butted . The system can then be anchored in place to prevent the pipe ends from opening up to the maximum end gap when pressurised .
Angular Deflection
GRINNELL Flexible Couplings are capable of accommodating angular deflection .
Expansion/Contraction
GRINNELL Flexible Couplings are capable of accommodating pipe thermal movements provided they are properly gapped and a sufficient quantity of flexible couplings are used . Note that flexible couplings will not accommodate both full maximum linear movement and the maximum available angular deflection concurrently at the same joint .
If it is desired to have both deflection and linear movement available, then the system should have sufficient flexible joints to accommodate the requirement .
End Gap
Pipe Ends Gapped for Expansion
Pipe Ends Butted for Contraction
11⁄4 – 3
114.3 – 610.0
4 – 24
50% 25%
End Gap Reduction
The following values should be used as available pipe end movements for GRINNELL Figure 705, 707, and 716 Flexible Couplings:
Pipe End Movements
Pipe Size mm Inches
Cut Grooved mm Inches
Roll Grooved mm Inches
42.4 – 88.9
0 – 1.6
0 – 0.8
11⁄4 – 3 4 – 24
0 – 0.063 0 – 0.188
0 – 0.031 0 – 0.094
114.3 – 610.0
0 – 2.4
0 – 2.4
*Roll grooved joints provide half the available movement of cut grooved joints.
The deflection published is a maximum value . For design purposes the maximum deflection should be reduced to account for field practises as shown:
11⁄4 – 3
114.3 – 610.0
4 – 24
50% 25%
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Pipe Size mm Inches
Deflection
Maximum Pipe End Gap
42.4 – 88.9
Pipe Size mm Inches
Maximum Pipe Deflection Reduction
42.4 – 88.9
Design Data