API610, API671 Marketplace – Obtaining Approved Vendor Status

Guest Post: Jim Jones, Lovejoy Canada

Utilizing the standards of several worldwide associations ensures that the manufactured & supplied equipment will be consistent in quality for the end user performance criteria, regardless of where the products are sourced.

The American Petroleum Institute (API) and International Standards Organization (ISO) are two of the most respected standard associations globally and are especially in force in the North American oil & gas industry.

Our flexible coupling customers rely on these API  & ISO organizations technical committees to research and advise on conditions that may affect the high performance requirements of rotating equipment.

End users will either use these API / ISO standards for their equipment or enhance them to ensure they receive quality manufactured equipment that performs to the intended field conditions.

In the oil & gas industries and especially in the refining marketplace compliance to the API610, API671, API676 or ISO 10441 standards is required for a majority of flexible coupling applications. The AGMA 9000 Class 9 is also a base for coupling design and supply under the API standards.

The coupling compliance and approval process requires a review of either the applicable API Standards, the customer Standards or enhanced Standards incorporating both API and Customer requirements.

The approval process involves detailed review of the specific application criteria; examples would be material, tolerances, component design, speed considerations and balance for various flexible coupling rotating equipment installations.

One must understand why the customer has specified either the API/ ISO standards, the API / ISO package in conjunction with client’s specifications or client’s standalone requirements. 

By understanding our customer’s position the suppliers will have a positive effect on their submission for the  technical and supply approval process.

For more information on API couplings, please see the API 610 Standard - Coupling Highlights and API 671 Coupling Standard blog posts. 


About the Author: Jim Jones has several decade power transmission technical sales expertise. To tap into Jim's rich industry knowledge and experience, you can get to him through the Lovejoy webpage and/or LinkedIn. To find a highly qualified Lovejoy representative or distributor in your area please see Lovejoy's Find a Sales Representative or Find a Distributor tool. 

API 610 Standard - Coupling Highlights

The API 610 standard (with ISO 13709 as the Identical European standard) was created by the American Petroleum Institute to outline regulations regarding centrifugal pumps for petroleum, petrochemical and natural gas applications.  The standard covers multiple components (housing castings, bearings, mechanical shaft seals, etc.) within the pump system in addition to the coupling connection.

For the coupling connection the standard defaults to an all-metal flexible element spacer type coupling, commonly known as a Disc Coupling.  In addition, the Disc coupling is required to be designed to retain the spacer if a flexible element (disc pack) fractures thereby preventing the spacer from impacting the coupling guarding and have a minimum balance of class 9 according to the AGMA 9000 standard. 

The standard allows other couplings to be used (with Gear coupling being the leading alternate) but still requires the coupling to have a balance of Class 9 to obtain the API 610 certification.

An important item to consider is that couplings operating above 3,800 rpm the API 610 standard states the coupling must be balanced to meet the API 671 (ISO 10441) standard.  While this will not provide a coupling that meets all the API 671 requirements, it will deliver the proper coupling balance needed for the application.

Active Coupling Bore and Keyway Standards - What Are They & Where Can I Find Them?

The first thing to know about coupling bore and keyway standards is that there are quite a few currently active and available. Given your application and the origin of the product/shaft in question, you should be able to quickly determine what standard applies to you. (If not, call an application engineer at a coupling company you trust... and they will quickly point you in the right direction.) 

Active Standards include: 

In North America...

• ANSI/AGMA 9002-B04 - Bores and Keyways for Flexible Couplings (Inch Series)
• ANSI/AMGA 9112-A04 - Bores and Keyways for Flexible Couplings (Metric Series)
• ANSI/AGMA 9003-B08 - Flexible Couplings – Keyless Fits  
• ANSI/AGMA 9103-B08 - Flexible Couplings – Keyless Fits (Metric Edition)

• API STD 610 - Centrifugal Pumps for Petroleum, Petrochemical and Natural Gas Industries
• API STD 671 - Special Purpose Couplings for Petroleum, Chemical and Gas Industry Services 

• AIA/NAS NA0139 - Keyway and Key Slot Dimensions Metric (an Aerospace standard)

 

In Germany... 

• DIN 6885-1 - Drive Type Fastenings without Taper Action; Parallel Keys, Keyways, Deep Pattern
• DIN 7172 - Tolerances and limit deviations for sizes above 3150 mm up to 10000 mm; principles, standard tolerances and limit deviations (ISO 286 Addendum for larger sizes)

 

In Japan...

• JIS B 1301:1996 - Keys and their corresponding keyways

 

And Globally (ISO)...

• ISO 286-2:2010 - Geometrical product specifications (GPS) -- ISO code system for tolerances on linear sizes (Part 1: Basis of tolerances, deviations and fits & Part 2: Tables of standard tolerance classes and limit deviations for holes and shafts)
• ISO 3912:1977 - Woodruff keys and keyways
• ISO 3117:1977 - Tangential keys and keyways

In addition to these active standards, the Mechanical Power Transmission Association's excellent (and free) 18 page "Frequently Asked Questions on Metric Bores and Keyways in Couplings" PDF can be used to discover a number of no longer active (expired or withdrawn) bore and keyway standards. (Note: Unfortunately, the MPTA document does not provide a route to secure these documents... but at least they can confirm the standard you seek did in fact exist at one time.) 

To broadly and briefly touch on bore and keyway standards, the North American (inch/imperial) standards tend to be more straight forward with limited variation (derived off the shaft)... while the metric options tend to be much more diverse (and were largely derived off the bore hole and were fragmented by various national approaches). Case in point, the metric standard (ISO 286), calls out over 100 different shaft and bore tolerances! Fortunately, great strides have been made to popularize a much smaller subset of these metric possibilities...  and, today, many coupling manufacturers default to using just a few metric tolerances as their standard (with Js9 keyways, and H7 clearance fit or P7 interference tolerances for the bore being a very popular default).
  
And as a final (also free) reference: Lovejoy's Engineering Data PDF catalog, which covers both inch and metric shaft tolerances in great detail on pages ED-10 through ED-20. 

(Bonus Hint: Lovejoy's Engineering Data catalog does comply with and specifically reference ANSI/AGMA 9002-B04 and ANSI/AMGA 9112-A04...and does use Js9 keyways as well as both H7 & P7 as default metric tolerances... so, if your need is narrow in scope, you might possibly consider saving a few bucks by pulling the data you seek directly from Lovejoy.)