Union Sweat/NPT vs. Direct Sweat/NPT

hydronical

Why do some components have union sweat and union NPT connections, while other similar components have direct sweat and direct NPT connections? For example the Caleffi NA5453 DirtMag has union sweat and union NPT connections, while the Caleffi 5463 DirtMag has direct sweat and direct NPT connections...

Snowmelt

Here is my theory,Mir you put a union on everything you will be able to take them off. Some people are cheap and don't want to pay for that extra bonus.

SWEI

If the device was built with unions as part of its design, they just install the tailpieces for whatever system (sweat, NPT, or press) needed. I suspect those union threads are standard "G" style, which means you actually have even more options for piping if you need them.

The sweat version of the 5463 comes from Italy with BSP threads in the body. They install BSP x sweat adapters in those over here (using Loctite.)

hydronical

@hot rod - any additional thoughts on this?

hot_rod

In some products we use the Euro bodies which have BSP threads. So we just add tailpieces to adapt to sweat, NPT or press

If we start with a new forging or casting it can be machined to sweat or NPT

NPT requires a deeper socket to machine a tapered thread. BSP can be a shallow thread, which seals with a gasket or hemp