BS EN 12007-1:2012 pdf download – Gas infrastructure — Pipelines for maximum operating pressure up to and including 16 bar Part 1 : General functional requirements
5 Gas characteristics5.1Gas quality and family
The quality and family of gas supplied through a gas infrastructure shall be specified so that its characteristicsare known to system designers and pipeline operators. This specification includes all relevant characteristicswhich contribute to safe operation and combustion. Changes in the properties of the gas which fall outsidepre-determined operating limits shall be notified to pipeline operators in advance.
Gas may also be treated or conditioned for operational and maintenance reasons.EXAMPLE1 For the control of leakage.
EXAMPLE 2 For the control of icing conditions at pressure regulating stations and installations.
Safe operating procedures for systems supplying gases heavier than air shall recognize the tendency forthese gases to settle downwards should they escape from the system.
Gas supplied to end users should possess a distinctive odour.
Where gas is to possess a distinctive odour its presence in the atmosphere shall be readily detectable at allgas concentrations of 20 % of the lower explosive limit and above.Where the gas does not possess a naturaldistinctive odour one shall be added for the purpose.
The odorant,where added, shall be non-toxic and harmless for the concentrations employed in normalapplications, and the odour shall disappear after combustion.
An odorant may be omitted in gas delivered specifically for further processing or other special purposes. Inthis case alternative means shall be available to detect leaks.
5.3Toxicity and lack of oxygen
The potential toxic effects of gas constituents and the potential lack of oxygen shall be considered to ensuresafety in all work practices undertaken on the gas infrastructure, in using the gas and in dealing with escapinggas.
The characteristics of materials of pipes, fittings and components and the mode of construction of pipelinesshall be appropriate to the types of gas being supplied and the conditions under which they are operated.
Materials and products shall conform to the relevantEuropean Standards or, in their absence, to the nationalor other established standards and shall be of a quality fit for purpose.Consideration shall be given to theeffects of climatic conditions on material behaviour and its consequential influence on performance.Materialscan give a different technical performance in risk or long term behaviour when exposed to or stored underextreme climatic conditions.
EXAMPLE1 At lower temperatures the critical pressure for rapid crack propagation in polyethylene pipe is reduced.
EXAMPLE 2 At low temperatures in steel pipes loss of resilience can occur, and at high temperatures disbondment ofcoatings on steel pipes can occur.
NOTE The critical pressure for rapid crack propagation in polyethylene pipe is tested and verified according toproduct standards,e.g.EN 1555.
For further information, reference should be made to the specific standards for the materials concerned.
7 Design
Gas infrastructures are designed to provide a safe and continuous supply of gas. This design considerstechnical aspects and procedures together with environmental and safety aspects.
The gas infrastructure consists of pipeline components arranged in networks or single lines, with associatedpressure regulating stations or installations and connections to consumers via service lines.
NOTE During the design phase these parts of the system may be considered separately.
Basic data and design principles should be documented together with the actual data as the gas infrastructureis built.Data such as the diameter,material,design pressure,family of gas and routing maps should beavailable as long as the gas infrastructure is in operation, see 13.2.
7.2Basic design data
The design of any gas infrastructure, or part thereof, should commence with a study collecting relevant basicdata for the part of the gas infrastructure to be installed. This basic data shall include, but are not limited to thefollowing:
the family of gas;
anticipated gas flow;
design pressure;
construction materials;
layout of the existing gas infrastructure;
the need for pressure regulation; and
provisional routing of pipeline sections.