Jiang's blog: "amse"

e between adjacent convolutions of 7% after the pressure test required by NE-6230. (c) The ratio of the internal pressure at which the bel- lows will become unstable (squirm) to the equivalent cold service astm download pressure shall exceed 2.25. By definition, squirm shall be considered to have occurred if under internal pres- sure an initially symmetrical bellows deforms, resulting in a lack of parallelism or uneven spacing of adjacent convolutions at any point on the circumference. Unless otherwise specified, this deformation shall be construed as unacceptable squirm when the ratio of the maximum convolution pitch under internal pressure exceeds 1.15 for unreinforced and 1.20 for reinforced bellows. In the case of universal expansion joints, which consist of two bellows joined by a cylindrical section, compliance ansi/astm pdf with these crite- ria shall be satisfied by the entire assembly. No external restraints on the bellows shall be employed during squirm testing other than those which will exist after installation. (1) For single joints used in axial or lateral motion, the squirm test may be performed with the bellows fixed in the straight position at the maximum length expected in service; for rotation and universal joints, the bellows shall be held at the maximum design rotation angle or offset movement. In the case of single joints subjected to rotation movement, or of universal joints subjected to lat- eral offset movement, an instability condition as previously defined may or may not appear. Instead, movement of the convolutions may occur due to the superposition of the lateral internal pressure component on the applied rotation.

In such cases, that portion of the bellows deformation due to the design rotation angle or offset movement shall not be included in the deformation used to define squirm. (2) In the case of squirm tests, the equivalent cold service pressure is de fined as the Design Pressure multiplied by the ratio Ec fi Eh, where Ec and Eh are defined 17 For general information, see standards of the Expansion Joint Manu- as the modulus of elasticity of the bellows material at room facturers Association, Inc., 25 N. Broa e between adjacent convolutions of 7% after the pressure test required by NE-6230. (c) The ratio of the internal pressure at which the bel- lows will become unstable (squirm) to the equivalent cold service pressure shall exceed 2.25. By definition, squirm shall be considered to have occurred if under internal pres- sure an initially symmetrical bellows deforms, resulting in a lack of parallelism or uneven spacing of adjacent convolutions at any point on the circumference. Unless otherwise specified, this deformation shall be construed as unacceptable squirm when the ratio of the maximum convolution pitch under internal pressure exceeds 1.15 for unreinforced and 1.20 for reinforced bellows. In the case of universal expansion joints, which consist of two bellows joined by a cylindrical section, compliance with these crite- ria shall be satisfied by the entire assembly. No external restraints on the bellows shall be employed during squirm testing other than those which will exist after installation. (1) For single joints used in axial or lateral motion, the squirm test may be performed with the bellows fixed in the straight position at the maximum length expected in service; for rotation and universal joints, the bellows shall be held at the maximum design rotation angle or offset movement. In the case of single joints subjected to rotation movement, or of universal joints subjected to lat- eral offset movement, an instability condition as previously defined may or may not appear. Instead, movement of the convolutions may occur due to the superposition of the lateral internal pressure component on the applied rotation. In such cases, that portion of the bellows deformation due to the design rotation angle or offset movement shall not be included in the deformation used to define squirm. (2) In the case of squirm tests, the equivalent cold service pressure is de fined as the Design Pressure multiplied by the ratio Ec astm a53 fi Eh, where Ec and Eh are defined For general information, see standards of the Expansion Joint Manu- as the modulus of elasticity of the bellows material at room facturers Association, Inc., 25 N. Broa