Downhole Subs- Crossover subs

Downhole Subs and Crossover subs are a basic tubular component used in the downhole drilling operations.  Its primary purpose is to enable two components with different connections to thread together.  They can also be used as a disposable or sacrificial component used to protect and extend the life of high value drill stem components, these type of subs are referred to as Saver Subs.  There are a variety of shapes and sizes available for Crossover Subs, Top Subs, Float Subs and Circulating subs.  Lift subs are available as well, these are used to lift heavy tubulars during operations.  ISM Manufactured Lift Subs from solid heat-treated alloy steel to meet all API Specifications.


Crossover Sub Diagram


Industrial Screen and Maintenance (ISM) has worked with many of the Drilling Companies for manufacturing Crossover Subs and many other downhole subs used in the drilling operations.  For over 50 years ISM has proudly serviced the Oil & Gas community with High Quality CNC Machining and Machine Shop services specializing in all tapered, rotary shouldered connections including API, Grand Prideco and VAM.  Offering on stop for all services, design, manufacturing, inspections and re-threading or tubular thread repair services.  Full in-house Quality Control ensures that each threaded connection leaves ISM meeting all API Specifications.

We know you cannot afford downtime, Quality and Service are number one at ISM.  With two locations ready to serve you, Casper, WY and Grand Junction, CO with in-stock high yield alloys ready to manufacturer or service your Crossover Subs to keep your drilling operations running.

Grand Junction, Colorado (970) 245-4020  or Casper, Wyoming (307) 234-3547



ISM offers a variety of subs in AISI 4140/4145 heat-treated steel and non-magnetic stainless. Virtually any type of sub can be manufactured in-house to customer specifications. Listed below are a few examples:


  • Lifting Subs- Lift Subs are offered as a conventional design in a variety of sizes to provide ease of handling long products or heavy downhole components. Lift subs are specifically utilized during make-up or break-out operations. The sub’s elevator recess and connections are machined to fit the elevator and drill collar connections, as per API specifications
  • Crossover Subs- Cross-over subs and bit subs can be made for any drill string connection size and function needed. Manufactured from heat treated alloy steel and machined to meet API specifications. Designed solely to enable two components with different connections to thread together.
  • Saver Subs- Saver subs are used to extend the life of the drill stem component it is threaded up to by taking the wear caused by multiple connections. The saver sub is used a sacrificial connection sub because it can easily be repaired and is a low-cost replacement. Saver Subs are typically used in conjunction with a drilling rig’s Kelly or Top Drive transmission.
  • Float Subs- Float Subs are used to house the float valve and provide fluid flow control through the ID of the drill string. They prevent back flow of cuttings from plugging the drill bit jets when making connections. Float subs are available in a variety of sizes to accommodate the full spectrum of downhole drill stem sizes.
  • Custom Application Subs– ISM can manufacture any type and configuration to meet your drilling specifications.
  • Other Sub Names and Configurations Available; Circulating Sub, UBHO Mule Shoe Sub, Pump in Sub, Pup Joint Sub and many more.