Rotary Shouldered Connection JSS® Thread Inspection System

Thread Check Inc. offers the Gagemaker JSS™ Thread Inspection System for Rotary Shouldered Connections. Save time and money and cover a wide range of diameters and thread types with the most versatile thread measuring system available. The Gagemaker Thread Inspection System provides certain advantages over thread plug and ring gages.

  • Prevent Drill String Failures
  • Reduce Costly Rework Charges…
  • Ensure Stronger Joint Connections…
  • Great Quality Control than What’s Now Offered for Used Pipe

Thread Check Inc. offers the Gagemaker JSS™ RSC Thread Inspection System for Rotary Shouldered Connections including API Regular, Flush Hole, Internal Flush Hole, API Numbered Connections, H-90, PAC, ACME Regular, and many more types.

Gagemaker’s JSS® Thread Inspection System for Rotary Shouldered Connections is a revolutionary breakthrough in accurately gauging the quality of both new and used rotary shouldered connections. It’s now possible to avoid broken connections by identifying thread damage before it’s visually apparent and unfortunately too late. For years, the industry has relied on the interpretative “fit” of a thread ring or thread plug gage although these fixed limit Go and No/No a ring or plug gage cannot directly measure variation in pitch diameter. With the JSS™ system, an inspector can measure just a few key attributes and save hours of down time and thousands of dollars in rework charges.

Insert Identifiers

The first step in the quality process is to ensure the threading insert being used is correct for the job. Use the JSS™ Thread Insert Identifier Template to quickly verify that the correct threading insert has been selected as well as check the full topping profile of both internal and external inserts.

Inspection Setup

TDWIN Taper™ is the only software program dedicated to the manufacturing and inspection of downhole tubular connections. It has everything you need to machine, inspect, and document tubular connection threads. TDWIN Taper™ relies on API and industry standard tables and tolerances. TDWIN Taper™ displays connection drawings, inspection gage information, and setup and inspection reports. Simply, it is a must have for any machine shop.

Thread Form Inspection

Thread form accuracy is important if two connectors are to make-up properly. Using a JSS Thread Profile Gage and a JSS Thread Addendum Gage provide a quick check of the thread to ensure that the form is correct. Thread form verification ensures form accuracy. Also, checking thread form will ensure the first imperfect thread is fully deburred.

Thread form is defined as its profile in an axial plane for a length of one pitch. Most importantly, verifying thread form is a recommended inspection for API connections and ensures form accuracy.

Tapered Thread Pitch Diameter Inspection

Thread Check Inc. offers Gagemaker tapered pitch daimeter gages for accurately measuring P.D. connections on pipe threads. Inspectors are able to measure the P.D. on new and and used pipe threads. Using a pin location profile (LPP) and a PD 8000 RSC Series gage or a box location profile (LPB) with an IT-5104-RSC, the inspector is able to pinpoint early signs of stress, perform preventative maintenance and thus extend the life of their drill string connections. Using a Gagemaker tapered pitch diameter gages, operators can accurately control the connection's size during manufacturing and thus insure the thread cones assemble into interference properly when the connections ore torqued together. 

In the past, pitch diameter has been commonly ignored as long as the ring or plug gage threaded to an acceptable standoff. With a pin location profile (LPP) and a PD-8000-RSC Series gage, the process of locating and measuring the pitch diameter takes less than a minute. This minute of inspection can quickly decide the difference between good and bad connections.

Thread Lead Inspection

API Spec. 7 Mandated Requirement

Thread Lead is one of the most important thread elements to monitor. Not only is lead inspection an industry wide practice for rotary shouldered connections, it is an API Specification 7 mandated requirement. Lead error is most commonly generated by manual and CNC lathes not cutting properly.

Verifying thread lead is within tolerance is a required inspection according to API specification. Application of a Gagemaker Lead Gage to a setting standard and then to the product confirms that the lathe is cutting properly. Lead variation has a direct effect on pitch diameter and how two connectors go together when made up.

Thread lead is the distance between threads, measured on a plane parallel to the centerline of the threaded part. Lead error has a direct effect on functional diameter, stand-off, and thread flank engagement.

Gagemaker’s lead gages inspect pin and box connections for multiple pitches and thread forms. The gages provide dimensional verification of product print data on the thread’s true integrity.


  • Interchangeable contact points allow inspection on a variety of thread forms and sizes.
  • Inspect RSC threads as well as Tubing and Casing threads
  • Requires presetting using Gagemaker’s lead gage setting standards.

Thread Taper Inspection

API Spec. 7 Mandated Inspection

Thread taper is another inspection required by API Spec 7. For accurate taper inspections, use Gagemaker JSS Taper Gages to verify that the pin and box connectors will have matching tapers. As connectors are made up, taper errors can cause high stresses that eventually can lead to connection failure.

Thread taper is the change in pitch diameter over the length of a connection, typically designated in inches per foot. For all rotary shouldered connections, measuring thread taper is not only an industry wide practice; it is an API mandated inspection.

During the manufacturing process, taper must be accurately measured and quantified to avoid mismatched tapers. When under a service load, mismatched tapers between pins and boxes diminish proper thread engagement resulting in reduced connection performance.

Gagemaker’s IT-6000 and ET-7000 series gages are the best choice for measuring and controlling both pin and box taper values within the required specification limits. When RSC connections are properly manufactured utilizing Gagemakers precision taper gages, product performance is maximized.

Thread Height Inspection

API Required Inspection

The correct thread height maximizes the performance of any threaded connection and is a required inspection by the API. Thread height affects both the interchangeability and integrity of a thread assembly. Thread height is the distance between the crest and the root, normal to the axis of the thread.

Gagemaker Thread Height Gages provide immediate feedback on how the thread height compares to the specification requirements. A shallow thread height may allow the connection to pull apart under critical loads.

Inspecting thread height can also help to detect a chipped tool. Gagemaker Thread Height Gages inspect both internal and external thread height for a variety of thread forms and provide immediate feedback on the integrity of your threads.

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