Positive Guide Stem: High Pressure Equipment Company's patented
"Positive Guide" stem assembly virtually eliminates lower stem
rotation - one of the most common causes of premature stem failure. The
lower section stem is manufactured from hardened 17-4 PH stainless steel
for exceptional wear and corrosion resistance and can be easily serviced
with no special tooling required. The one-piece upper section stem eliminates
the need for continual adjustment and minimizes "loose handle"
backlash.
The Positive Guide Stem is standard for all AF4, AF6, HF4, HF6, and HF9
valves, and 60,000 psi HF2 valves.
Rolled Style Stem: This simple two-piece design is also non-rotating
and is ideal for smaller valves and for valves made from exotic materials.
The standard lower section stem is manufactured from hardened 17-4 PH stainless
steel. It is affixed to a one-piece upper stem requiring no periodic adjustment.
The two stem components are free to rotate independently of each other,
thereby minimizing rotation of the lower stem against the valve seat.
The Rolled Style Stem is standard for all AF1, AF2, NFA, NFB, LF4, LF6
valves, 30,000 psi HF2, XF4, and XF6 valves, as well as most valves requiring
stems made from exotic materials. It is optional for any valve normally
supplied with a Positive Guide Stem.
Pinned Stem Design: This variation on the Rolled Style Stem is
a three-piece design in which the lower stem is pinned into a freely-rotating
stem guide. It has all of the advantages of the rolled style stem, with
the additional benefit of a replaceable lower section stem.
The Pinned Stem Design is standard for all NFC, NFD, NFF, NFH, LF9, LF12,
LF16, and HF16 valves. | 
