Axially and rotationally locked modular valve assembly system

A method of controlling fluid flow through a tubular positioned in a subterranean wellbore comprising:

• running a workstring into a wellbore, the workstring having a modular valve assembly positioned therein;
• the modular valve assembly having a first valve assembly attached to a second valve assembly, each valve assembly comprising:
• an upper housing and a lower housing attached to one another at a non-threaded interlocking joint, the attached upper and lower housings defining a longitudinal throughbore;
• the upper housing having a valve seat formed therein;
• a plunger biased into contact with the valve seat, the plunger movable between a closed position wherein the plunger is in contact with the valve seat, and an open position wherein the plunger is spaced apart from the valve seat;
• the lower housing retaining the plunger in the throughbore;
• and
• the interlocking joint rotationally locking the upper and lower housings to one another against relative rotation in any direction and axially locking the upper and lower housings to one another;
• flowing a fluid through the first and second valve assemblies, fluid pressure moving the plungers from closed positions to open positions to allow fluid flow through the valve assemblies;
• and
• moving the plungers from open positions to closed positions in response to a decrease in fluid pressure.