Codes and Standards

Codes and standards utilised for casing tubulars are wide ranging and include many organisations on an international basis. A Drilling Engineer needs to be aware that the generation of a well design and specification of the tubulars may require the use and study of a variety of codes, standards and guidelines. He should also ensure that the most up-to-date documentation is available, as all codes, standards and guides undergo periodic review and updates.

They include, but are not limited to the following:

American Petroleum Institute (API)

National Association of Corrosion Engineers (NACE)

Institute of Petroleum (IP)

American Society of Mechanical Engineers (ASME)

American Society for Testing and Materials (ASTM)

American National Standards Institute (ANSI)

International Standard Organisation (ISO)

Committee for European Normalisation (CEN)

2.2.3.1 API Codes – General Application

The most universally used standards relating to the specification of oilfield tubular goods has been and still is API.

API Committee 5 – Tubular Goods Specifications and Publications

The API appointed a committee, named Committee 5, on Standardisation of Tubular Goods which publishes, and continually updates, a series of Specifications, Standards, Bulletins and Recommended Practices covering the manufacture, performance and handling of tubular goods. They also license manufacturers to use the A-PI Monogram on material that meets their published specifications, so that field personnel can identify materials that comply with the standards. Their pronouncements are almost universally accepted as the basis for discussions on the properties of tubulars.

However, this does not mean that everyone accepts the published performance data as the best theoretical representation of the parameters. The forum consists both of users and manufacturers.

API documents covering casing are grouped into three categories.

2.2.3.1.1 Specifications

These documents govern the manufacture, material properties and dimensions of Oil Country Tubular Goods (OCTG), threads and equipment. They are generally considered binding between buyer and seller if referred to in purchase orders. They would assist in specifying a well design.

2.2.3.1.2 Recommended Practices (RPs)

These publications provide recommended (but not necessarily binding) actions which should be followed when performing such activities as inspection. RPs are often utilised in the industry but are not generally considered binding upon the seller unless they were included as part of the purchase order.

2.2.3.1.3 Bulletins

These documents are published primarily for information purposes, though they may become part of a commercial contract if they relevant.

2.2.3.1.4 API Committee 5 Documents

The documents published by API relevant to casing design are:

1. API SPEC 5CT, ‘Specification for Casing and Tubing’.

Covers seamless and welded casing and tubing, couplings, pup joints and connectors in all grades. Processes of manufacture, chemical and mechanical property requirements, methods of test and dimensions are included.

2. API STD 5B, ‘Specification for Threading, Gauging, and Thread Inspection for Casing, Tubing, and Line Pipe Threads’.

Covers dimensional requirements on threads and thread gauges, stipulations on gauging practice, gauge specifications and certifications, as well as instruments and methods for the inspection of threads of round-thread casing and tubing, buttress thread easing, and extreme-line casing, and drillpipe.

3. API RP 5A5, ‘Recommended Practice for Field Inspection of New Casing, Tubing, and Plain-End Drill Pipe’.

Provides a uniform method of inspecting tubular goods.

4. API RP 5B1, ‘Recommended Practice for Thread Inspection on Casing, Tubing and Line Pipe’.

The purpose of this recommended practice is to provide guidance and instructions on the correct use of thread inspection techniques and equipment.

5. API RP 5C1, ‘Recommended Practice for Care and Use of Casing and Tubing’.

Covers use, transportation, storage, handling, and reconditioning of casing and tubing.

6. API RP 5C5, ‘Recommended Practice for Evaluation Procedures for Casing and Tubing Connections’.

Describes tests to be performed to determine the galling tendency, sealing performance and structural integrity of tubular connections.

7. API BULL 5C2, ‘Bulletin on Performance Properties of Casing and Tubing’.

Covers collapsing pressures, internal yield pressures, and joint strengths of casing and tubing and minimum yield load for drill pipe.

8. API BULL 5C3, ‘Bulletin on Formulae and Calculations for Casing, Tubing, Drill Pipe and Line Pipe Properties’.

Provides formulae used in the calculations of various pipe properties, also background information regarding their development and use.

All of the above documents should be checked to ensure their validity and that they are the most up-to-date editions available.

2.2.3.2 National Association of Corrosion Engineers (NACE Standard MR0175-99)

This standard covers the materials requirements for all oilfield equipment, including downhole tubulars and production equipment. The NACE Standard MR0175-99 is entitled ‘Standard Material Requirements – Sulphide Stress Cracking Resistant Metallic Materials for Oilfield Equipment’.

The NACE standard is only concerned with the resistance of materials to sulphide stress cracking in sour conditions. However, there are other failure mechanisms that may occur in the presence of hydrogen sulphide and need to be taken into consideration, when selecting materials for sour service.

The first step in applying the NACE methodology is to determine whether ‘sour conditions’ as defined by NACE MR0175-99 exist. The standard defines sour environments as fluids containing water as a liquid together with hydrogen sulphide at a level exceeding certain criteria.

The Drilling Engineer will need to use the NACE standard to determine the partial pressure of hydrogen sulphide in the gas phase (if present) and thus assess material requirements.

2.2.3.3 Institute of Petroleum

There are two documents the Drilling Engineer should be aware of for well design.

The first is a Model Code of Safe Practice Part 17 Well Control during the Drilling and Testing of High Pressure Offshore Wells, a set of guidelines on issues to consider for high pressure, high temperature (HPHT) wells.

The second is a set of ‘Guidelines for Routine and Non-routine Subsea Operations from Floating Vessels’ and should be used to consider issues associated with conductor and surface casing design as part of the wellhead system.

2.2.3.4 ASME/ASTM/ANSI

These standards are utilised as part of the various API standards. For example, mechanical tensile testing on longitudinal testing, using ASTM A370 under API Spec 5CT.

2.2.3.5 International Standard Organisation (ISO)

ISO describes itself as ‘the specialised international agency for standardisation’. Its members are the national standards organisations of 91 countries. ISO publishes international standards emanating from several technical committees and sub-committees. A technical board comprising one representative from each national body governs ISO. The Central Secretariat co-ordinates ISO operations, administers voting and approval procedures, maintains and interprets the directives that set out the procedures and rules, and publishes the international standards. ISO is responsible for all fields of international standardisation except electrical and electronic.

ISO Technical Committee 67 (ISOITC 67) – Oil Industry Matters

ISO/TC 67 was reactivated in 1988, because the international upstream industry was increasingly recognising the need for good international standards that could be accepted and applied worldwide.

As part of the reactivation, the scope of ISO/TC 67 was extended to the standardisation of the materials, equipment and offshore structures used in drilling, production, refining and the transport by pipelines of petroleum and natural gas. The work programme developed was primarily in the fields of drilling and production but also includes machinery and equipment used in refining and petrochemicals.

2.2.3.6 Committee for European Normalisation (CEN)

CEN is the European counterpart of ISO. It consists of the members of the national standards organisations of the EC countries.

It aims to achieve the goal of the EC, ie to improve the international competitive position of European industry.

One of the methods to achieve this is the removal of technical trade barriers by:

Harmonising Standards (with emphasis on health, safety and environment) into European Norms (ENs)

Introducing Directives (which will become law at national level, referring to relevant ENs)

Harmonising Certification

Testing and Certification in Europe

2.2.3.7 Co-operation between ISO, CEN and API

As all CEN members are also ISO members, a close co-operation exists. The co-operation between ISO and CEN has been formulated as follows:

‘It is declared policy of the community that whenever possible CEN/CENELEC shall implement international standards in a uniform way but where international standards have not yet been developed or where existing standards need to be adapted to European situations, CEN and CENELEC will develop ENs in anticipation of international ones.’

As part of the Harmonisation Legislation for Europe 1992 the EEC commission requested the CEN to introduce ENs. As the upstream oil and gas industry is dominated by API standards, the CEN requested the ISO to investigate the feasibility of converting API standards into ISO standards and subsequently into ENs.

It was decided to divide the API standards into three classes:

Class 1: API standards to be circulated by the ISO central secretariat under the

‘fast-track’ procedure, meaning 1 to 2 years

Class 2: API standards to be further discussed to modify them prior to submittal to the ISO

Class 3: API standards requiring significant study prior to moving forward as international standards

In 1988 API offered more than 70 of its standards to ISO, to he the basis of international standards. In 1989 an ISO Advisory Group classed several of these as suitable for adoption without technical modification and ISOICS agreed to ‘fast-track’

these to become international standards. ‘Fast-track’ means that the API document is given an ISO Number, front cover and foreword but is otherwise presented as-is. So far API Bull. 5C3, API RP5C1 and API Std 5B have been ‘fast-tracked’.

The ISO foreword addresses issues such as equivalent references to American national references, certification and the API Monogram.

The industry is now well established regarding the process of ‘transferring’ API standards. It is no longer seen as appropriate that all the A-PI standards offered should become ISO standards. Some may be better left with API because the helpful and discursive style of many (RPs and bulletins in particular) is lost when re-formatted to comply with ISO directives.

An example of the API/ISO convergence process is API 5C3 Bulletin on Formulae and Calculations for Casing, Tubing Drill Pipe and Line Pipe Properties. This contains the requirements of ISO 10400 Petroleum and Natural Gas Industries – Formulae and Calculations for Casing, Tubing, Drill Pipe and Line Pipe Properties.