ISO 23555-1-2022 pdf free download – Gas pressure safety and control devices for use in gas transmission, distribution and installations for inlet pressures up to and including 10 MPa — Part 1: General requirements.
4.3Strength types
This document considers the following strength types of controls:- Type IS: (integral strength type);
Type DS: (differential strength type).5Materials
5.1General
The quality of materials, the dimensions used and the method of assembling the various parts shall besuch that construction and performance characteristics are satisfactory for the intended application.
Compliance of materials shall be verified by reviewing technical documentation and verifying specificconformity assessment as presented in 5.3.
ln the documentation, the selected material standards shall be declared as presented in 5.3.5.2 Requirements
5.2.1 Requirements for metallic materials
5.2.1.1 Pressure-containing parts and inner metallic partition walls
The pressure-containing parts, including those that become pressure-containing parts in the event;of diaphragm or differential pressure seal failure, and the inner metallic partition walls shall beconstructed of materials:
chemically resistant to the fuel gases listed in Clause 1 and to the additive substances normally usedfor odorization and conditioning of gases;
resistant to the permissible impurities in the gas;
complying with the relevant international material standard for pressure application (chemicalcomposition, mechanical characteristics and test procedures) and the restrictions given in Table 2.NOTEA list of possible materials is given in Annex A.
5.2.1.2 Auxiliary devices, threaded sealing plugs, integral process and sensing lines,connectors and fasteners
Auxiliary devices, threaded sealing plugs, integral process and sensing lines, connectors and fastenersshall be constructed of materials:
chemically resistant to the fuel gases listed in Clause 1 and to the additive substances normally usedfor odorization and conditioning of gases;
resistant to the permissible impurities in the gas;
complying with the relevant international material standard (chemical composition,mechanicalcharacteristics and test procedures) and the restrictions given in Table 2.
NOTEA list of possible materials is given in Annex A
5.2.2 Requirements for non-metallic materials5.2.2.1General
Non-metallic materials used for functional parts in contact with the gas shall be chemically resistantto the fuel gases listed in Clause 1 and to the additive substances normally used for odorization andconditioning of gases.Furthermore, these materials shall be resistant to the permissible impurities inthe gas.
5.2.2.2 Requirements for elastomers (including vulcanized rubbers)
Elastomeric materials shall be in accordance with the requirements shown in Annex B for fueldistributed gases in accordance with the classification of gas families and groups according to EN 437.The following supplementary requirements should be considered:
– for diaphragms in communication to environmental conditions, the resistance to ozone;
– for seat rings and other elastomeric components subjected to erosion by flowing gas, the abrasionresistance and tear strength related to the design of the relevant components.
The characteristics of elastomeric materials shall be proved by a declaration of compliance with theorder type 2,1 in accordance with 1SO 10474:2013.
For spare parts made of elastomeric material, the installation, operation and maintenance manualof the control shall specify appropriate packing and storage requirements in order to minimize thedeterioration of the elastomeric material (against UV radiations and ozone cracking).
5.2.2.3 Requirements for non-metallic materials different from those in 5.2.2.2
The resistance to liquids of functional non-metallic parts shall meet the requirements in Table 3. Thechange in mass after immersion for 7 days with a tolerance of t2 h at (23± C in test liquid B inaccordance with ISO 1817,and after drying, shall comply the requirements in Table 3.ISO 23555-1 pdf download.