Bowers Group (UK) Ltd

Bowers Group supplies industry with an unrivalled choice of high quality Precision Measuring Equipment, Bespoke System Design and Laboratory-based UKAS Calibration Services.

Bowers Group offer an extensive range of products from leading brands including Bowers, Moore & Wright, Baty, INNOVATEST, Trimos, Sylvac, Wyler and ACCRETECH. Products ranges include, Bore Gauging, Optical Measuring, Materials Testing, Height Gauging, Levelling, Thread Measurement and Surface, Form and Geometry.

New API Inspection Requirements for July 2018

New API Inspection Requirements for July 2018

The American Petroleum Institute (API) has released the Sixteenth edition of the 5B Specification for Threading, Gauging, and Inspection of Casing, Tubing, and Line Pipe Threads, with an effective date of July 1st, 2018. The new specification has major changes that companies need to be aware of in order to conform and properly maintain their API license. Luckily, Bowers Group can help!

New Mandatory Attribute Inspections

There are several new mandatory attribute inspections to be aware of, including crest diameter, form, addendum, and tooth thickness/groove width. Examples and methods of gauging these attributes are fully described in Section 5 of the sixteenth edition. API has also created new dimensions and tolerances for the majority of API licensed connections. 

Meet API Inspection Requirements with Gagemaker

As the exclusive distributor for the Gagemaker product line in the UK, Bowers Group can offer plenty of ways to help customers prepare for the new inspection requirements, including tools, advice, and information.

For example, the Gaugemaker MRP Pitch Diameter & Ovality Gauges are a key piece of equipment for API compliance. Available from Bowers Group, the MRP series of Pitch diameter gauges measures the internal and external pitch diameters of tapered threaded connectors. The gauges use two pivoting thread shoes that rest on the crests of the threads, with the diameter variation being detected by the indicator readout.

Details of Threading and Gauging Specification Requirements

This specification covers dimensions, tolerances, and marking requirements for API threads and the gauges that control the acceptance criteria for the threads. Thread element gauges, instruments, and requirements for the inspection of threads for line pipe, round thread casing, round thread tubing, and buttress casing connections are included.

Thread dimensions shown without specifications (or shown as NA) are not subject to inspection of diameter, ovality, and addendum. Thread dimensions shown without tolerances are related to the basis for connection design and are not subject to measurement to determine acceptance of product.


Thread inspection applies at the point of manufacture prior to shipment, to inspection at some intermediate point, to inspection subsequent to delivery at destination, and to inspection by inspectors representing the purchaser or the manufacturer. The manufacturer may, at his or her option, use other instruments or methods to control manufacturing operations; but acceptance and rejection of the product is determined by the results of inspection made in accordance with the requirements of this specification.

Thread inspection is performed using instruments designed to measure either the functional relationship of multiple thread elements or measure an individual thread element. The inspection requirements include measurements of standoff, diameter, ovality, addendum, taper, lead, height, and angle of thread that are applicable to threads having 111/2 or less turns per inch (0.45 or less turns per mm). Ring and plug gauges are designed to measure the functional size of an internal or external thread. Individual thread elements listed are measured with one or more specific instruments.

Find out more about our range of Gagemaker products here -

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