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NEN 3656

Requirements for submarine steel pipeline systems

active, Most Current
Organization: NEN
Publication Date: 1 March 2022
Status: active
Page Count: 390
ICS Code (Iron and steel pipes): 23.040.10
scope:

General

This standard gives minimum requirements that are laid down relating to safety aspects for people, the environment and property for the construction, installation, commissioning and decommissioning and operational management of submarine pipeline systems for the transport of substances.

This standard also provides guidelines for the design of components and elements that are part of submarine pipeline systems, such as shut-off valves, launching and receiving facilities for pigging activities.

This standard does not contain requirements for flexible pipes and flexible risers.

The scope of this standard is limited to group I pipeline systems, intended for the transport of hazardous substances (see A.2.1) and to production water pipelines in the oil and gas extraction industries.

NOTE 1 In this standard submarine pipelines for the transportation of (non-)flammable and non-toxic, such as CO2, N2 , AR, and aqueous liquids, are also considered to be group I pipeline systems. Specific properties of the fluid are also included in the risk assessment of the design (see 6.3).

The requirements are applicable for new submarine pipeline systems to be constructed or modification of existing submarine pipeline systems. Modification of existing systems means:

- replacement of submarine pipeline sections/submarine pipeline elements in the same route;

- diversions of submarine pipeline sections/submarine pipeline elements to another route;

- work on, repair or replacement of submarine pipeline sections/submarine pipeline elements during the operational management of the submarine pipeline system (see Clause 11);

- modification of process conditions (temperature, pressure, fluid).

Submarine pipelines include: all pipelines in or on the sea bed of the continental shelf (whether or not in territorial waters), from the low water line (LAT, lowest astronomical tide) up to and including the connections to the installation (see Figure 1 en Figure 2), and of which the typical system limits are depicted in detail in Figures 3, 4, 5, 6 and 7.

The landfall, the pipeline section between LAT and the first shut-off valve after crossing the water retaining structure, meets the requirements of NEN 3650-1 and - within the safety zone of the crossing with the water retaining structure - those of NEN 3651 (see Figure 1).

NOTE 2 In this standard LAT means the low water line as defined in the Wet grenzen Nederlandse territoriale zee (Netherlands Territorial Sea (Demarcation) Act) of 9 January 1985 [1].

NOTE 3 In some cases, e.g. a 'schaardijk' (dyke immediately next to the river) with a rather steep underwater bank, the safety zone according to NEN 3651 may extend further than LAT. Therefore, NEN 3651 is also applicable to that section of the submarine pipeline.

NOTE 4 This standard may also be used for pipelines in areas with similar ambient conditions, such as inland seas and estuaries. Industrial installation pipelines on (production) platforms (see system limits) and any temporary (flexible) pipelines are outside the scope of this standard.

This standard contains provisions and references for the landfalls of submarine pipelines on (offshore) platforms and for the landfall of the submarine pipeline up to and including the first shut-off valve after the crossing with the main water retaining structure on land.

The pressure control system of the submarine pipeline is controlled by the shut-off valves on the landfalls on the (offshore) platforms and, if present, by the first shut-off valve after the main water retaining structure on land. Shut-off valve stations in crossings on the seabed are primarily intended for containing the pressure system for adaptations in the seize of the submarine pipeline system (disconnecting/connecting extensions or repairs in the submarine pipeline system).

NOTE 5 For the pressure system of submarine pipelines that land on land, the NEN 3650 series, NEN 3651 and NEN 3656 are consulted.

The system limits between industrial installations and Group I submarine pipeline systems are part of the (pressure) limitation of the submarine pipeline system, as shown in Figures 2, 3, 4, 5, 6 and 7. The standard does not contain any requirements for pipework of industrial installations under the scope of the Warenwetbesluit drukapparatuur (Netherlands Commodities Act Decree on pressure equipment).

NOTE 6 The system limits of a submarine pipeline are defined in the pipeline design. The design requirements of the pipeline section above the water subsequently meet the requirements of NEN 3656 or the essential safety requirements within the technical regulations of the Pressure Equipment Directive 2014/68/EU [2].

System limits between submarine pipeline and industrial installations

The system limits between the submarine pipeline and industrial installations indicate which technical standards are applicable for the submarine pipeline elements, such as shut-off valves and appendages, which are necessary to contain and blow off the pressure system of the submarine pipeline.

NOTE 1 In this standard isolating shut-off valves are considered to be an essential part of the submarine pipeline system, in addition to the Mijnbouwbesluit (Netherlands Mining Decree), in which a pipeline is understood to be the part between two isolating shut-off valves.

This standard is also applicable to launching and receiving facilities of pigs which are used in the operational phase during the lifespan and which are part of the submarine pipeline system. The launching and receiving facility may be applied for internal cleaning, internal inspection, distributing corrosion inhibitor or for fluid management of the submarine pipeline.

This standard may also be applied to launching and receiving facilities which are temporarily installed and which are not present in the operational phase of the submarine pipeline during its life span.

The design explicitly states whether the launching and receiving facility is of a temporary of fixed nature. The system limits are explicitly stated in the design.

NOTE 2 PED 2014/68/EU (Pressure Equipment Directive) is not applicable to components of submarine pipeline systems. It is mandatory that the shut-off valve meets the design requirements of the submarine pipeline system in question. By law it is not permitted to apply PED CE marking to components of the submarine pipeline system. However, the principles to meet the essential safety requirements will remain fully applicable.

The system limits as given in Figures 1 to 7 of the submarine pipeline system are aligned on the provisions for industrial installations and are in accordance with PED 2014/68/EU (Pressure Equipment Directive). According to PED 2014/68/EU a pipeline (submarine pipeline) consists of all pipelines or specially designed pipeline elements for the transportation of a liquid or substance from and to an industrial installation (onshore or offshore). The pipeline (submarine pipeline) begins at the limits of the industrial installation (offshore topside) and includes the last isolation element within the limits of an industrial installation (offshore topside). The submarine pipeline consists of all equipment which is specially designed for the pipeline (submarine pipeline). This includes, among other things, launching and receiving facilities for pigs, isolation shut-off valves, pressure alarm systems and security systems.

NOTE 3 During the installation of the pipeline, temporary launching and receiving facilities have the function of draining it or when it is definitely decommissioned to flush it. In both these situations low pressures and other liquid media are used.

NOTE 4 Submarine pipelines that function as the main connections of the pipeline transport system (the so-called trunk lines) are usually fitted with launching and receiving facilities for pigs. Submarine pipelines that are connected with a main connection (the so-called trunk line) by means of a branch, are usually not fitted with launching and receiving facilities for pigs (the so-called spurline).

NOTE 5 When the drain and the blow off are only applicable to the submarine pipeline, they are within the system limit of NEN 3656. When the drain and the blow off are also connected to the processing unit, they are within the scope of PED/WBDA (PED/Netherlands Commodities Act Decree on pressure equipment).

NOTE 6 When the drain and the blow off are only applicable to the submarine pipeline, they are within the system limit of NEN 3656. When the drain and the blow off are also connected to the processing unit, they are within the scope of PED/WBDA (PED/Netherlands Commodities Act Decree on pressure equipment).

Shut-off valves

Shut-off valves in submarine pipeline systems are preferably flanged shut-off valves in order to facilitate repairs or exchanges. The shut-off valve design must be able to withstand the design conditions of the submarine pipeline system.

All shut-off valves in a submarine pipeline system are fitted with an identification number (tag number). The design specifications are stated on the identification plate.

Shut-off valves meet the requirements of NEN-ISO 14313, submarine shut-off valves meet the requirements of NEN-EN-ISO 14723.

NOTE 1 Shut-off valves in submarine pipeline systems meet the requirements of API 6D. This is permissible since this standard was the basis for NEN-ISO 14313 and NEN-EN-ISO 14273.

NOTE 2 The International Association of Oil & Gas Producers (IOGP) has specified additional requirements for shut-off valves. The IOGP Specification S-562 Supplementary Requirements to API Spec 6D - Ball Valves gives quality requirements which may be applied by choice. For automatic shut-off valves with a safety function, it is advised to apply the highest quality monitoring level according to Quality Specification Level-4 (QSL-4) of the IOGP Specification S-562 during their manufacturing.

The quality for fire resistance of the shut-off valve is demonstrated by means of a test certificate according to NEN-EN-ISO 10497.

Valve management systems and actuators are designed and manufactured in accordance with accepted standards in Europe. The specification of the valve actuator defines the torque requirements for the valve's functioning, with a suitable safety margin to compensate for deterioration and increase in friction as a result of aging and maintenance. The minimum closing times of these shut-off valves are pointed out.

Automatic security shut-off valves at least meet Safety Integrity Level-1 (SIL-1) or higher according to NEN-EN-IEC 61508-5 and the NEN-EN-IEC 61511 series.

NOTE 3 For the verification of the probability of failure of safety shut-off valves (Probability of Failure on Demand (PFD)) the individual probabilities of failure of the components in the safety loop from Appendix 6-B: Generic Component Failure Database of PGS 4:1997, version December 2005 (Red Book), may be used in order to verify the SIL qualification of the safety loop. Only periodically the functioning (opening/closing) of the safety shut-off valve needs to be determined and it will be verified whether there is no unacceptable leakage to the environment which may result in an explosive atmosphere. SIL qualifications do not need to be verified before the life span evaluation of a submarine pipeline system.

Document History

NEN 3656
March 1, 2022
Requirements for submarine steel pipeline systems
General This standard gives minimum requirements that are laid down relating to safety aspects for people, the environment and property for the construction, installation, commissioning and...

References

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