have lubricating properties.
1.4.3 Tightening Torque. Due to application-specific
variables such as materials, wall thickness, operating
pressures, etc., no guidance is given in this Standard
regarding joint-tightening torque. However, joints
should be tightened beyond the hand-tight engagement
position. Advancing the joint past hand-tight creates
interference between external and internal thread flanks,
produces a seal (with the use of a sealant), and helps
prevent loosening of the joint. Overtightening may be
detrimental to the sealing function of the joint.