Cast vs. fabricated deck fittings: which one belongs on your deck?
ASTM A27 castings, A36 plate and SM490A fabrications compared — with real Sinooutput examples.
Short answer
Cast-steel fittings (ASTM A27) are the economical, proven standard for bitts, kevels and chocks and arrive as-cast for easy welding. Fabricated fittings from steel plate are chosen where you need larger sizes, lower weight or a smoother surface — Sinooutput fabricated roller buttons are stronger than cast and 25% lighter.
Cast steel: the proven default
Most Sinooutput deck hardware — double and single bitts, kevels, button, open and closed chocks, Panama chocks and mooring eyes — is cast from ASTM A27-70-36 steel. Castings are sold as-cast, with no paint or surface finish, so welders can fit them to the deck of any barge or workboat quickly and safely.
Fabricated: when size, weight or surface matter
- Fabricated button chocks (UMC-158A, 12") are made from ASTM A36 plate and bead-blasted.
- Fabricated double bitts (UMC-500 / UMC-600) reach 18" and 24" bollard diameters in SM490A plate, with optional stainless bollards and an epoxy + polyurethane finish.
- Heavy-duty thru-deck fabricated roller buttons (UMC-200) use hot-rolled high-strength plate: stronger than cast, 25% lighter, with a smooth bollard that reduces line friction.
Thru-deck vs. flush weld
For towing loads, thru-deck single bitts and kevel chocks add rigidity and keep the fitting from tearing out of the deck under extreme load. Flush-weld styles are faster to install where loads are moderate.
A simple rule
Default to cast for standard sizes. Move to fabricated when you need bollards above 14", a weight saving, or the gentlest possible surface for synthetic rope.
Frequently asked questions
Why are Sinooutput castings sold unpainted?
So they can be welded to the deck quickly, easily and safely without removing paint first.
How much lighter are fabricated roller buttons?
About 25% lighter than comparable cast-steel roller buttons, while being stronger.
