Drill Stem Subs

Subs are part of most drill strings. They connect drilling components with different connections and act as low-cost, replaceable parts that extend the life of more expensive drill stem components.

Longmar supplies drill stem subs to API Spec 7-1 from 2-7/8" to 14" OD in 110–130 ksi material, made from traceable heat-treated 4145H alloy steel bars (higher-alloy steel available on request). Every sub carries unique permanent serialization traceable to certified mill data. API numbered and other standard connections, as well as CET®, CDS® and CTX™ double-shoulder connections, are available. Threads are phosphated and can be cold rolled to NS-1 and made up/broken out on request.

Standard configurations

• Straight OD
• Reduced section (bottleneck)
• Swivel sub
• Lift sub

Non-standard configurations

• Crossover sub (box × pin, box × box, pin × pin)
• Bit sub with float recess
• Saver sub and top drive sub
• Circulating sub, pump-in sub, side-entry sub
• Casing running subs and special application subs

Common types

• Crossover sub: crosses over from one connection size to another, or acts as a disposable part to protect a more expensive member.
• Lift (pickup) sub: lifts BHA components such as motors, jars and drill collars from the catwalk to the rig floor; the drillable version can stay in the BHA while drilling.
• Bit sub: connects the bit to the first BHA component; 3-1/8" to 11" OD, straight or bottleneck.
• Top drive / saver sub: matched to the top drive and drill pipe specification.

Drawings and data sheets are available on request.