This post “Oil and Gas Pipeline Design, Construction and Operation Guidelines” covers the system employed for the service of transporting hydrocarbon fluid or fluids associated with operations related to Petroleum exploitation, production, refinery and product distribution. Contact Aziza M.E.S Limited for pipeline construction and maintenance services.

Subtitles to expect are Liquid Petroleum Transportation Piping systems, Pipelines Construction Requirements, Minimum Requirements for Pipeline Burial, Procedure for Pipelines System Inspection and Testing, and Gas Transmission and Distribution pipeline system.

We did not cover Open Access Pipeline. That’s, Pipeline system operated within the open access regime.

We prescribed the general standard procedures for oil and gas pipelines design, construction and operation.  The guidelines covered the construction, commissioning, operation and maintenance of pipelines and their ancillary installations in oil and gas industry. Click Guidelines for Gas Transmission and Distribution pipeline system. The standard is in line with the Nigerian Oil Pipeline Acts Cap 338 LFN 1990.

 

What is Pipeline and Pipeline System?

Pipeline is a long pipe, typically underground, for conveying oil, gas, etc. over long distances. A pipe or tubing used in the transportation of hydrocarbon resource from the first gathering manifold to all the facilities required for processing, distribution and export.

 

Read: Pipelines Corrosion Control Standard Requirements

 

Oil Pipeline Act Cap 338 LFN 1990 defines pipeline as a means for the conveyance of mineral oils, natural gas and any derivatives or component, and any substance (including steam and water) used or intended to be used in the production or refining or conveying of mineral oils, natural gas and any of their derivatives or components.

While a Pipeline System is all parts of those physical facilities comprising a particular pipeline through which hydrocarbon resource flows, including pipe, valves, and other appurtenances attached to the pipeline such as, pump or compressor stations, regulating and metering stations, block valve stations, electrical equipment stations for Cathodic Protection etc.

Liquid Petroleum Transportation Piping systems

Liquid Petroleum shall include crude oil, refined products, Natural Gas Liquids, condensates, and liquefied Petroleum Gas.

Minimum Pipeline Systems Design Criteria

The design criteria prescribed herein shall apply to new pipeline systems, relocation or replacement and upgrading of existing pipelines.

  • The two commonly acceptable grade of line pipes for this service shall be either those materials conforming with the ASTM A106 Grade B or API 5L Grade B for low pressure range and any of the API 5LX range for high working pressure or large diameter pipeline where a lower grade will require excessively thick walls to cope with the desired working pressures
  • The line pipe shall be seamless in fabrication and be Electric Resistance Welded (ERW) or Double Submerged Arc Welded (DSAW) types only.
  • The design shall generally be in accordance with the standard ASME B31.4-2019 and its subsequent revisions published by the American Society of Mechanical

Read: Permits/ Approvals for Pipeline System Engineering & Construction

 

pipeline construction services

Engineers under the title “Pipeline Transportation Systems for Liquids and Slurries”. In addition to the general provisions of the code, special attention shall be paid to the following:

i. Wave and current loads shall be taken into account in the stress calculation of pipelines to be laid at sea or riverbeds without burial.

ii. Calculation of limit stresses due to sustained load, thermal expansion, and occasional loads where applicable shall be strictly in conformity with paragraph 402 of the code.

iii. Design and material selection of the pipeline components such as tees, elbows, bends, valves, fittings etc. shall in all respects, conform to chapters II and III of the code.

iv. No used fitting of an existing pipeline shall be reused on a new pipeline without its original specification being identified and confirmed to be capable to perform the new service

v. Threaded joints at both internal and external portions shall all be of the tapered line pipeline thread type conforming with API SPEC 5B or NPT in accordance with ASME B1.20.1-2013

vi. The least nominal wall thickness of the threaded portion of the pipe shall not be less than the value specified in ASME B36.10M-2018

vii.       All threaded joints shall be on sections of the pipeline above ground.

viii.      If two or more pipelines are to be connected in manner that one will operate at a pressure higher than the other, they shall be so designed that the pipeline system operating at the lower pressure shall not be subjected to any pressure greater than its licensed operating pressure.

ix. All pipe fittings, valves and equipment connected to the pipeline shall have manufacturers’ ratings which are equal to or greater than the proposed maximum operating pressure of the pipeline.

  • All pipelines shall have Remote Monitoring System Remote Monitoring systems installed on them.

Note: Other internationally recognised standards approved by the NUPRC shall be accepted.

 

Read: Oil & Gas Permits / Licenses

 

Minimum Pipelines Construction Requirements

This procedure shall apply to new pipelines construction and replacements of existing pipelines. The pipeline construction shall generally follow the steps outlined in Chapter V of the standard ASME B 31.4-2019 or its subsequent revisions. The construction code shall be guided by the following:

  1. The licencee shall inform the Department prior to the start of construction. Nominated technical officers of the Department shall continue to provide regulatory guidance.
  2. All metallic pipeline material to be buried shall be coated with any of the following systems – coal-tar enamel, Asphalt enamel, polyethylene tape, epoxy, asphalt mastic, urethane or other material specially approved by the Department for specific reasons.
  3. All surface pipelines shall be painted, raised and maintained above ground on permanent supports.
  4. All pipeline construction shall be carried out in a manner that will minimize disturbance to the environment.
  5. Special precautions shall be taken to protect the pipeline from washouts, unstable soil, landslides, or any other hazards that may cause the pipeline to move or be subjected to abnormal loads.
  6. All pipelines welding shall be in accordance with the provisions of API STD 1104-2013 while welding inspection shall be by non-destructive method preferably using Radiographic method contained in API STD 1104-2013 or its later editions.

 

Read: LPG Tanks & Terminal Construction

 

Minimum Requirements for Pipeline Burial

a. Ditching for the pipeline shall follow good pipeline practice and consideration for public safety as provided for in the Standard API RP1102-(R2017) shall be followed.

b. Minimum soil coverage of pipelines shall be as follows:

  • Dry land – 1.0 meter.
  • River crossings and riverbeds – 1 meter.
  • Drainage ditches, Railroad and Highway Crossing – 1.5 metres
  • Rocky Areas – 0.9 metres
  • Swamp – 1.0 meter
  • Shipping Channels – 2.0 metres

c. At railroad and highway crossings, in addition to the specific requirement of the relevant Government Agency responsible for these infrastructures, the following precautions shall be taken:

  • Installations of carrier pipe or casing shall be in accordance with API RP1102-(R2017).
  • The casing shall be insulated from its carrier pipe support and shall extend to both sides of the railroad or highway. In the alternative the crossing could be of a thicker wall line pipe covered with compacted full and protective reinforced concrete slab.
  • All surface lines shall be similarly buried with casing protections or special construction specified in (ii) above at such crossings.
  • Pipeline warning signs shall be conspicuously displayed at both the entry and exit points of the pipeline crossings of railroads, highways, other pipelines, and rivers.

d. The licencee shall identify any pipeline laying within 30 metres radius of its area of ground disturbance during pipeline construction.

 

Read: NCEC Certificate Registration

 

e. The licencee before commencing any ground disturbance in a populated or controlled area shall first accurately locate the position and alignment of the pipeline with markings and distinguishable warning signs at adequate intervals.

f. If a pipeline lies within the 30-metre radius of construction, the licencee shall endeavour to first of all, locate the pipeline in question and manually excavate it till it is sufficiently exposed for purpose of identification and avoidance by the construction equipment.

g. The same precaution in (f) above shall be taken by any third party undertaking any construction activity within this radius of safety zone around any pipeline.

h. Once the pipeline has been so exposed, no excavation within 1-meter radius of it, shall be allowed

i. Where in the opinion of the Department, it is desirable to do so, it may direct that an existing pipeline located within the construction zone of a new pipeline in a populated or controlled area be either completely de-pressurized, operated at reduced pressure, or be otherwise protected throughout the period of ground disturbance in its vicinity.

j. The same precautions as stipulated in (e) and (f) above shall apply to pipeline crossings.

k. Mainline block valves shall be installed on the upstream side of major river crossings and at pump stations while check valves shall be installed downstream of river crossings.

l. Mainline valves shall be installed at other sensitive locations of the pipeline such as in industrial, commercial, and densely populated areas where construction activities may pose particular risks of damage to the pipeline. The pipeline right of way in these areas shall be clearly marked with signs for ease of identification.

 

Procedure for Pipelines System Inspection and Testing.

The Licencee shall notify the Department of the completion of construction of the pipeline or any sections of it which is due for testing giving notice of not less than one month from the date of commencement of such tests. Inspection shall be guided by the following:

The pipeline material and construction shall be inspected visually and examined radio graphically according to the procedure enumerated in Chapter VI of the reference standard ASME B 31.4 – 2019 and internationally recognised standards approved by NUPRC.

a. All tests shall generally be hydrostatic and be conducted in a manner that will ensure the protection of life, property, and the general environment of the pipeline.

b. The entire length of the pipeline shall be tested to the designed rated pressure while any in-line pressure vessel or prefabricated manifold on the pipeline shall be tested to the manufacturer’s specifications in accordance with the Mineral Oils Safety Regulations (MOSR).

c. The pressure recording instruments to be used for the tests shall have a valid calibration certificate which should not be more than a year of issue and the chart record of the test shall be continuous and legible and all test results and any remedial action taken shall be submitted to the Department for approval before commissioning of the pipeline. The Accuracy of the pressure recorder shall be within two per-cent (2%) of its range.

d. Unless otherwise permitted by the NUPRC, pressure test duration shall not be less than four hours of continuous test both for leaks and material failures. Buried pipeline of up to 100 meters in length and all surface running pipelines could be tested for less periods but not lower than (1) hour.

e. The general guiding rule for environmental protection shall be as follows:

  • Where the test pressure shall result in a hoop stress greater than 75 percent of specified minimum yield strength of the pipeline based on the nominal wall thickness, and the pipeline does not cross or pass within 100 metres of any environmental protection arrangement, otherwise permission of the NUPRC would be required to ensure that adequate contingency plans have been made for protecting the environment.
  • Any pipeline crossing watercourses shall be tested with adequate environmental precautions taken.

Guide to Pipeline Testing

  • Unless otherwise authorized by the NUPRC, the following shall generally apply:
  • The actual test pressure throughout the duration of test shall not exceed 110% of the minimum yield strength of the pipe material; hence the testing equipment shall be pre-set not to produce more than this pressure during the test.
  • The test medium shall be water except with special permission of the NUPRC
  • All buried pipelines shall be tested to a pressure not less than 1.25 times the internal design pressure.
  • Surface pipeline transmitting liquid petroleum or gas shall be tested up to a pressure not less than 1.25 times the internal design pressure.
  • All pipelines shall be tested to a minimum pressure of not less than 700 kilopascals unless otherwise permitted by the NUPRC. Punctual
  • The maximum test pressure in all cases shall not result in a hoop stress, greater than 110 percent of the specified minimum yield strength of the pipe material based on its nominal wall thickness.
  • Valves and fittings on the pipeline under test shall not be subjected to a pressure greater than the manufacturer’s test pressure rating during the test.

Conclusion, we believe the provided guidelines for Oil and Gas Pipeline Design, Construction and Operation system will help your company. For Pipeline Engineering, Construction, Operation, Installation and Maintenance, Aziza M.E.S Limited (Aziza Group) is your right partner across Nigeria and other continents. Feel free to contact.