3A-13H Bevel Seat ACME Hexagonal Sanitary Union Nut

3A-13H Hexagonal Collar Geometry and ACME Threading

This 3A-13H hexagonal union nut is the female threaded tightening collar for sanitary bevel seat unions. The six-flat hex exterior allows wrench engagement, while the stepped internal bore (B) captures the shoulder of a bevel seat plain ferrule (14P) and pulls it onto the tapered nose of an ACME-threaded ferrule (15T).

Material Options and Reference Source Scope

The primary series specifications specify SS304 or SS316L stainless steel across the 1" to 4" range. Companion 1"–4" 13H bevel-seat hex nut references list inch dimensions; confirm whether 304 or 304L stainless steel is required when ordering.

Tabulated Metric Dimensions (A, B, H, SW)

Across the six sizes on the 3A-13H bevel seat hex nut drawing (mm), thread A, bore B, height H, and hex width SW are: 1.0" (38.02×8TPI ACME, B=30.3, H=23, SW=46), 1.5" (51.40×8TPI, B=42.9, H=24.6, SW=61), 2.0" (64.99×8TPI, B=56, H=27, SW=76.5), 2.5" (78.40×8TPI, B=69.1, H=30.7, SW=92), 3.0" (91.92×8TPI, B=82.2, H=32.5, SW=106.5), and 4.0" (120.14×6TPI ACME, B=108.9, H=38.1, SW=137.6).

Selection and Thread Pitch Checks

Sizes 1.0" through 3.0" use an 8 TPI ACME thread whereas the 4.0" size transitions to a coarser 6 TPI ACME thread. Confirm nominal tube OD and stainless steel grade (304 vs 316L) before ordering.