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API updates 4F manufacturing standard for onshore and offshore steel structures

Published by , Deputy Editor
Oilfield Technology,

API released the fifth edition of Specification 4F, a manufacturing standard that applies to both onshore and offshore well structures to ensure operational safety and sustainability.

This specification provides requirements and recommendations for the design and construction of steel structures commonly used in natural gas and oil drilling and well servicing operations.

The new 4F Specification is applicable to all new steel derricks, masts, substructures, and crown block assemblies that are manufactured in accordance with this specification. API’s Standard Department developed and published the new Specification as part of the API Monogram licensing programme, which affords facilities the ability to apply an API mark to products that are manufactured in accordance with API requirements.

This latest version of Specification 4F makes a significant change from previous versions of the standard by incorporating the 15th edition of the American Institute of Steel Construction’s (AISC) code for Allowable Strength Design. Adding the latest AISC code to the 4F Specification ensures that all new derricks, masts, and substructures are manufactured using steel that meets the latest requirements for strength, reliability and safety.

The new API standard also adds a new uniform method of rating these structures by establishing two product specification levels (PSLs) that define two levels of technical and quality requirements. For example, PSL 1 requirements will reflect practices currently being implemented by a broad spectrum of the manufacturing industry.

Whereas under PSL 2, the requirements reflect both what manufacturers are already implementing, as well as additional steps to enhance strength of the materials and reliability. For example, under 4F the loading of the material within heat-treatment furnaces shall be such that the presence of any one part does not adversely affect the heat-treatment of all the components. In addition, all temperature and time requirements for heat-treatment cycles shall be met using the manufacturer’s or processor’s written specification. Actual heat-treatment temperature and times shall be recorded, and heat treatment records shall be traceable to relevant components.

The new API standard also recommends using a risk management methodology that employs a Structural Safety Level (SSL) for drilling and well structures. The SSL level reflects the degree at which a structure’s operation may be affected once it is deployed. Each structure will be qualified for use based on two SSLs – the first will address any anticipated event that may affect the structure’s operation, and the second will address any unexpected event.

The 4F Specification also helps manufacturers assess and take account for wind speeds that are primary concerns when operating in the offshore environment. The new edition includes calculations to be used by the manufacturer to assess and create designs to protect against the wind forces to structures when operating offshore.

API Training will be hosting a webinar on 29 July at 11:00 a.m. ET on the Fifth Edition 4F Specification. The webinar follows the publication of the standard earlier this month by API’s Global Industry Services (GIS) division and is made available through

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