API standard 616, latest edition is applicable for land-based heavy duty and aeroderivative industrial gas turbines. The API standards 614, 615, 670, 671 and 678 also form a part of API 616. Many gas turbine manufacturers, however, do not follow the API standards strictly, and follow their own specifications which have. API Standard 617 Axial and Centrifugal Compressors and Expander-compressors EIGHTH EDITION SEPTEMBER 2014 374 PAGES $240.00 PRODUCT NO. This International Standard was developed from the API Std 671, 3rd edition, 1998. It is intended that the 4th edition of API Std 671 will be identical to this International Standard. Users of this International Standard should be aware that further or differing requirements may be needed for individual applications. The 2016 edition lists API standards, recommended practices, equipment specifications, other technical documents, and reports. For upstream, API publications cover offshore structures and floating production systems, tubular goods, valves and wellhead. IHS is your source for all the latest API standards and keeps you.

Originally published in the February 2012 issue of Pumps & Systems. Oil and gas industry customers are increasingly asking original equipment manufacturers (OEMs) to balance their couplings to ensure that their equipment runs smoothly. While balancing is intended to reduce machine vibration, it can be an unnecessary and costly expense.

Manufacturing methods and design tolerances usually result in sufficient balance so that couplings meet industry standards without additional balancing procedures. API Balance Standards The oil and gas industry relies on the American Petroleum Institute’s (API) 610 standard as the internationally accepted set of standards for pumps and associated equipment, such as couplings, in rotating equipment. The standard, which is now in its 11th edition, has three key clauses that address balancing couplings: • OEMs must provide all-metal, flexible element, spacer-type couplings that meet American National Standards Institute/American Gear Manufacturers Association (ANSI/AGMA) 9000 Class 9 requirements. (API 610 6.2.2) • Couplings that operate faster than 3,800 revolutions per minute must meet the International Standards Organization (ISO) 10441 or API 671 requirements for component balancing and assembly balance check. (API 610 6.2. Install Hindi Fonts In Xp. 2 e) • OEMs must balance couplings to ISO 1940-1 Grade G 6.3 if the customer requests it.

(API 610 6.2.3) The first clause requires couplings to meet ANSI/AGMA 9000 Class 9, which states that the coupling’s center of rotation must not deviate more than 0.05 millimeters (0.002 inches) from the rotating axis of the machine to which it is connected. While OEMs must produce couplings accurately to achieve this standard, couplings that meet this specification typically do not require additional balancing. The second clause states that OEMs must balance the components in higher-speed applications in compliance with API 671, a mandatory specification that leaves little room for error. OEMs can use a balancing machine to achieve this specification. For a standard coupling, the transmission unit and each hub normally have to be balanced to ISO 1940-1 Grade G 0.66, and the assembly check should be balanced to ISO 1940-1 Grade G 6.6. High-speed applications that require this level of balance are often fitted with keyless or two-key precision shaft ends. If the hubs have standard single keys, balancing the transmission unit should suffice.

The third clause requires OEMs to balance couplings to ISO 1940-1 Grade G 6.3 if the customer specifies it. Balancing the transmission unit to ISO 1940-1 Grade G 2.5 results in a better level of installed balance, however, particularly with standard bore and keyed shafts. Some projects rely on earlier editions of the API 610 standard, particularly the 8th edition. That edition includes a requirement for balancing all components to ISO 1940-1 Grade G 1.0, which, in practice, means balancing the transmission unit and both hubs. This requires that OEMs balance the hubs before machining the keyway, wasting time and resources. Furthermore, the ANSI/AGMA 9000 Class 9 coupling standard is the only mandatory requirement in the latest API standard. Balancing Hubs with Standard Keyways The standard steps for balancing hubs with keyways are: • Bore the hub to the correct size • Balance the hub as a component • Machine a keyway into the bore Because of the key and keyway’s tolerances, the volume of material removed above the key varies significantly, which also affects the balance of the hub in an average-sized coupling.