Bolt preload scatter and relaxation behaviour during tightening a 4 in-900# flange joint with spiral wound gasket

Abstract

Gasketed bolted flange pipe joints are found prone to leakage during operating conditions. Therefore, performance of a gasketed flange joint is highly dependent on the proper joint assembly with proper gasket, proper gasket seating stress, and proper preloading in the bolts of a joint. For a gasketed flange joint, the two main concerns are the joint strength and the sealing capability. To investigate these, a detailed three-dimensional non-linear finite-element analysis (FEA) of a gasketed joint is carried out using a spiral wound gasket. FEA results are compared with the experimental results and are found to be in good agreement, hence validating the FE model developed. Bolt scatter, bolt bending, and bolt relaxation are considered to be the main factors affecting the joint performance. In addition, the importance of proper bolt tightening sequence and number of passes and the influence of elastic and elasto-plastic material modelling on joint performance are also presented. Stress variation in the flange due to flange rotation highlighted joint strength, and gasket contact/seating stress variation highlighted the sealing performance during bolt up. Modelling the non-linearity of the spiral wound gasket using non-linear elements highlights reduced joint strength and sealing performance. Summarizing, a dynamic mode in a gasketed joint is concluded, which is the main reason for its failure.

Keywords

bolt relaxation gasketed joint dynamic tightening sequence spiral wound gasket

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References

Abid

Nash

D. H.

Joint relaxation behavior of gasketed bolted flanged pipe joint during assembly. In 2nd WSEAS International Conference on Applied And Theoretical Mechanics (MECHANICS'06), 2006, pp. 319–325.

Abid

Experimental and Analytical studies of conventional (gasketed) and unconventional (non gasketed) flanged pipe joints (with special emphasis on the engineering of ‘joint strength’ and ‘sealing’). PhD Thesis, 2000.

Abid

Nash

D. H.

Bolt bending behavior in a bolted flanged pipe joint: a comparative study. In ASME International PVP Conference, 2006, pp. 1–9.

Fukuoka

Takaki

Finite element simulation of bolt-up process of pipe flange connections. J. Press. Vessel Technol., 2001, 123, 282–287.

Fukuoka

Takaki

Finite element simulation of bolt-up process of pipe flange connections with spiral wound gasket. J. Press. Vessel Technol., 2003, 125, 371–377.

Abid

Baseer

3-D nonlinear finite element analysis of gasketed flanged joint under combined internal pressure and different temperatures. J. Eng. Mech. ASCE, 2006, 133(2), 1–8.

7 ANSYS Inc., ANSYS elements manual, 7th edition, 2006.

8 ASME Boiler and Pressure Vessel Code, Section VIII, Part D, American Society of Mech. Eng., 1998, New York, USA.

Nagata

Shoji

Sawa

A simplified modeling of gasket stress-strain curve for fem analysis in bolted flange joint design. In ASME International PVP Conference 2002, vol. 433, pp. 53–58.

10.

10 European Sealing Association. Guidelines for safe seal usage - flanges and gaskets. Report no. ESA/FSA 009/ 98, 1998, pp. 1–40.