the convergence error comes because of the following reasons:
A)If for "+y "the pipe is lifting at the support because near by support is not placed at nul point please change the locatiion of nearby supports.Or put "Y" restraint.
b)A nearby axial stop may be the problem.
C)see the not sliding positions of the nodes.
d)if in "Lateral directiions "system has guides or cross guides with gaps which are not touching hence no need of friction.
Or reduce the friction stiffness in Configuration file.
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DJ PAUL
jr. stress engineer