Pressure Testing Methods Dvgw g 469

DVGW Code of Practice G 469 Pressure testing methods for pipelines and installations for the supply of gas ISSN 0176-3490 Price group 5 DVGW German Technical and Scientific Association for Gas and Water P.O. Box 14 03 62 D-53058 Bonn Telephone: (02 28) 9188-5 Telefax: (02 28) 9188-9 90 E-Mail: [email protected] Internet: www.dvgw.de

to note this English version is not authorized by DVGW (at the moment) Preface to the 1st edition The DVGW Set of Rules on gas contains a number of Technical Rules regarding the construction of gas lines and installations in the field of gas supply in which reference is made to specific pressure testing methods. This Code of Practice presents a systematic compilation of pressure testing processes for pipelines and installations in the field of gas supply. In the DVGW Technical Rules on the construction and operation of gas supply pipelines and installations, provisions have been set out for the different pressure testing methods and their application by referring to this Code of Practice. Eschborn, October 1977

DVGW German Technical and Scientific Association for Gas and Water

Preface to the 2nd edition After the newly developed, field-tested pressure measuring method with air using a precision pressure gauge, such as a deadweight pressure tester, has yielded positive results, the DVGW Committee “Transmission Pipelines” took the decision to revise DVGW Code of Practice G 469, which had appeared in its first edition in October 1977, under its direction and in agreement with DVGW Committees “Components in Gas Installations”, “Rough Gas Measurement”, “Local Gas Distribution”, “Regulating Stations” and “Compressor Stations”. In addition to the new pressure measurement method with precision pressure gauge which helps to simplify and improve measurement processes with air, other amendments and supplementary information has been provided in order to adapt this revised edition of the Code of Practice to the state-of-the-art in the field of pressure testing methods.

Eschborn, July 1987

Contents Preface to the 1st edition

Preface to the 2nd edition

1

Scope

2

General

2.1

Purpose of pressure test

DVGW German Technical and Scientific Association for Gas and Water

2.2

Classification of pressure test methods

2.3

Test media

2.3.1

General

2.3.2

Hydrostatic tests

2.3.3

Pneumatic tests

2.3.4

Pressure tests with operating gas

2.4

Methods - Overview

2.5

Pressure test - process sequence

2.6

Measuring equipment

3

Description of pressure test methods

3.1

Visual test - Method A

A

3.1.1

Visual test with water (single pressurization) – Method A 1

A1

3.1.2

Visual test with water (dual pressurization) – Method A 2

A2

3.1.3

Visual test with air – Method A 3

A3

3.1.4

Visual test with operating gas – Method A 4

A4

3.2

Pressure measuring methods – B

B

3.2.1

Hydrostatic pressure testing (single pressurization) – Method B 1

B1

3.2.2

Hydrostatic pressure testing (pressure applied twice) – Method B 2

B2

3.2.3

Pressure testing with air – Method B 3

B3

3.2.3.1

General

3.2.3.2

Simplified pressure measuring – Method B 3.1

B 3.1

3.2.3.3

Pressure measuring with precision measuring equipment (e.g. deadweight pressure tester) – Method B 3.2

B 3.2

3.3

Differential pressure measuring with air – Method C

C3

3.3.1

General

3.3.2

Differential pressure measurement with test bottle – Method C 3.1

C 3.1

3.3.3

Differential pressure measurement with pressurizer – Method C 3.2

C 3.2

3.4

Pressure measurement/volumetric test – Method D Pressure measurement volumetric test (dual pressurization) – Method D 2

D D2

4

Regulations and Technical Rules

Appendix

Diagrams 1 and 2

1

Scope

This Technical Rule applies to the pressure testing of pipelines or installations for public gas supply, such as pipelines for the transmission or distribution of gas, compressor stations, pressure regulating and metering stations. However, it does not apply to the pressure testing of pipelines

according to DVGW-TRGI (DVGW Code of Practice G 600). This Technical Rule may be applied to pressure tests performed on other pipelines and installations which do not serve public gas supply, provided that the specific characteristics of the gases and any other applicable provisions are taken into account.

2

General

When applying the pressure test methods described in Section 3, the rules set out in the relevant DVGW Codes of Practice must be observed (cf. Section 4). The pressure test method to be applied depends on the materials used, the types of joints between individual pipeline or installation components and on the intended scope of application. All pressure parameters or pressure values stated in this Technical Rule are overpressures above ambient atmospheric pressures.

2.1 Purpose of pressure tests The pressure tests described herein may either be applied on their own or they may be combined. They are carried out to appraise the strength and/or tightness of the system to be tested and thereby serve to prove the safety of the pipelines or systems.

2.2 Classification of pressure test methods Pressure test methods are classified depending on whether –

the pressurized pipeline or system is inspected externally during the time of testing (visual inspection method),

–

the test pressure in the pipeline or system is measured during the time of testing (pressure measuring method),

–

the test pressure in the pipeline is compared with the pressure of a reference device (such as a test bottle or deadweight pressure tester)(differential pressure method) during the test.

–

in addition to the test pressure in the line also the water volume required to raise the pressure is being measured (pressure measurement /volumetric method).

2.3

Testing media

2.3.1

General

Irrespective of Section 2.2, test methods differ from one another in that for pressure testing either a fluid test medium (water) is used or a gaseous test medium (air, operating gas). In place of water also other suitable fluid test media may be used; hereafter, only water will be mentioned. In place of air also other suitable gaseous test media may be used; hereafter, only air will be mentioned. In place of operating gas also mixtures consisting of operating gas and inert gas may be used; hereafter, only operating gas will be mentioned. The different test methods always must be carried out with specific test media because of reasons related to the measuring equipment to be used or for safety reasons; differential pressure testing is, for example, always carried out with air and pressure measurement/volumetric testing always with water.

2.3.2 Hydrostatic tests A distinction is made regarding hydrostatic testing between single or dual pressurization whereby special attention should be paid to the following: –

These tests must only be conducted at water and ambient temperatures of above +4 oC. Special measures must be taken for lower temperatures. Sufficient time must be allowed for the temperature of the water filled into the pipeline and its surroundings to even out.

–

The water used for testing must not act aggressively on the materials; the pipeline and water must be free of contaminants as these may impair the tests and later also operation.

–

The pipeline or installation components must be filled with water in way which ensures that they are sufficiently free of air. Already when applying the test pressure the ratio between the amount of water that has been filled in and the subsequent increase in pressure may point to insufficient venting or the presence of major leaks. For the checking of air freeness confer to pressure testing methods B 1 or B 2.

–

Generally, when carrying out pressure tests with water in the course of which pipelines will be subjected to 95% of minimum yield strength (cf. strength characteristic K, as in DIN 2470 Part 1 and Teil 2, DIN 30 690Part 1, for example) volumetric measurements must be made when applying the pressure.

2.3.3 Pneumatic tests The following must be observed when carrying out pneumatic tests: If a test pressure is applied which is sufficiently higher than 6 bar and if the entire pipeline or system or parts of it have not been tested priorly with the same or a higher test pressure, special safety precautions must be taken (such as destructive tests on all girth welds, tighter construction or

testing supervision).

2.3.4 Pressure tests with operating gas This test is carried out with operating gas with the testing pressure corresponding to the working pressure of the feeding line or system. If, when carrying out pressure testing with operating gas, higher pressure nitrogen is added, for example, the test pressure in the pipeline or system may rise to a level which is above that of the working pressure of the feeding line or system. Furthermore, Section 2.3.3 applies analogously regarding the special safety measures to be observed.

2.4 Methods - Overview If the pressure tests are classified by the method of testing A visual method B pressure measurement C differential pressure measurement D pressure-/volumetric measurement and by the test medium or pressure which is applied 1 water/once 2 water/twice 3 air 4 operating gas the following pressure test methods result an overview of which is given in Table 1.

2.5 Pressure test – process sequence The time plan of a pressure test can be broken down into different segments. As an example, Fig. 1 presents a schematic description of the process sequence for a pressure test which is carried out in accordance with method B 2. Process sequence 1 = first application of test pressure 2 = first holding time (test pressure) 3 = first lowering of pressure 4 = second holding time (at least 2 bar at the high point of the line) 5 = second application of test pressure 6 = third holding time (test pressure) 7 = relieving of pressure

2.6 Measuring equipment All measuring equipment used for testing must be in perfect working order. For the setting and measuring of test pressures, master pressure gauges of at least class 0.6 must be used. Other necessary measuring devices and their respective requirements are dealt with in the Sections on test methods B 1, B 2, B 3, and C 3. Water

Prüfmedium

Air

Test method Visual method Pressure measuring method

A B

once 1 A1 B1

Differential pressure measuring method

C

–

–

Pressure-/volumetric method

D

–

D2

Table 1: Pressure testing methods - overview

twice 2 A2 B2

3 A3 B3 B 3.1 B 3.2 C3 C 3.1 C 3.2

–

Operating gas 4 A4 – –

–

pressure test pressure

at least 2 bar at high point of pipeline

Fig. 1: Process sequence of pressure testing for pipelines according to test method B 2

3

Description of pressure testing methods

3.1

Visual test - Method A

The purpose of visual testing of a pipeline or system is to visually assess its tightness, and, if the testing pressure significantly exceeds maximum allowable operating pressure, also its strength when exposed to the testing pressure. For all visual test methods, the pipeline or system to be tested must be exposed; in particular pipe joints, fittings, valves, pressure vessels, etc. must be accessible for inspection while the test is being carried out.

3.1.1 Visual test with water (single pressurization) – Method A1 The test pressure is determined before commencement of the test and must not exceed 95% of strength parameter K of the pipes or system components, as according to DIN 2470 Part 1 and Part 2, DIN 30 690 Part 1, for example. The test pressure, however, must at least be 1.3 times the maximum allowable operating pressure at the high point. After filling and venting (cf. Section 2.3), the test pressure is applied at a maximum rate of increase of 3 bar/min and for pipelines and systems as a rule held for 3 hours. The holding time may be reduced for component assemblies of systems according to DIN 30 690 Part 1 and for pipelines in systems according to DVGW-Code of Practice G 496. During this time, the pipeline or component assemblies of the system must be inspected for tightness in particular at the joints and where parts have been installed (flanges, sockets, valves etc.).

3.1.2 Visual test with water (dual pressurization) – Method A 2 The test pressure is determined before commencement of the test and must not exceed 95% of strength parameter K of the pipes or system components, as according to DIN 2470 Part 1 and Part 2, DIN 30 690 Part 1, for example. The test pressure, however, must at least be 1.3 times the maximum allowable operating pressure at the high point. After filling and venting (cf. Section 2.3), the test pressure is applied with a maximum rate of increase of 3 bar/min and held for approximately 90 minutes. After having reduced the pressure to the lowest possible level (holding time 30 minutes), which at the high point must still be at least 2 bar, and after having increased the test pressure a second time, the pressure is held again for at least 90 minutes. During this time, the pipeline or component assemblies of the system must be inspected for tightness in particular at the joints and where parts have been installed (flanges, sockets, valves etc.).

3.1.3 Visual test with air – Method A 3 The test pressure must be based on the Technical Rules of the DVGW which are applicable to the pipeline or system to be tested. Where these rules stipulate minimum values, the exact test pressure must be defined before beginning with the test. After having applied the test pressure at an increase rate which must be defined beforehand (up to a maximum of 3 bar/min), the test pressure in

the line or system is held until all pipeline joints, valves, flanges, etc. have been tested for tightness with a foaming agent. The pipeline joints to be tested must be free from grease or coatings. It is recommended to repeat the test with foaming agent after having lowered the test pressure to approximately 2 bar.

3.1.4 Visual test with operating gas A4 The test pressure corresponds to the operating pressure and must not exceed 1.0 time the maximum allowable operating pressure even if nitrogen (cf. Section 2.3) has been injected. After the filling process has been properly completed, the test pressure is increased at a rate which must be determined beforehand (up to a maximum of 3 bar/min.). During the increasing of pressure and after an appropriate holding time, all pipeline joints, valves, flanges and similar items must be tested for tightness with a foaming agent. Any joints to be tested must be free from grease and coatings.

3.2 Pressure measuring methods B When applying pressure measuring methods, the strength and tightness of a pipeline is evaluated on the basis of the pressure survey obtained during pressure testing by precision measurements. That is why these methods are in particular suitable for buried pipelines which do not provide the accessibility needed for visual tests. When evaluating the pressure survey the temperature variations of the test medium, the pipe wall and of the surrounding soil and/or ambient atmosphere must be taken into consideration. The pressure test proper only begins when the temperatures of the test medium and adjoining soil or atmosphere have balanced out.

3.2.1 Hydrostatic pressure testing (single pressurization) – Method B 1 The test pressure must be at least 1.3 times the maximum allowable operating pressure at the high point, while the strength parameter K of the pipelines, as according to DIN 2470 Part 1 and Part 2, for example, must not be exceeded. The exact test pressure must be determined before beginning with the test. If the tests are carried out in seasons during which frost might occur, any exposed sections of the pipeline must be protected against freezing. In order to confine temperature fluctuations to a minimum, the pipe trench must be filled out as best as possible. The non-filled share must amount to less than 3 % in relation to pipe length. If possible, vales and mechanical joints should be easily accessible. If possible, pipe sections to be tested must not exceed a length of 15 km or a volume of 3000 m³. For volumes in excess of 3000 m³, measuring accuracy must be enhanced. To conduct the test, a special test rig is required (such as a construction site trailer) which is equipped with the following measuring equipment: –

for the gauging of pressure: –

class 0.6 master pressure gauge

–

pressure gauge with an accuracy of at least 0.1 % (e.g. deadweight pressure tester, differential pressure gauge)

–

recording manometer

–

level gauge (measuring range: 1.5 times of test pressure)

All pressures occurring during the course of testing must be recorded with a recording manometer. –

for the measuring of temperatures: –

thermometer for surrounding air (scale division 0.5 oC)

–

Sufficiently long thermometer for the pipe wall of buried pipe segments, which means that it should at least extend to the crown of the pipe (scale division 0.05oC, recommended measuring range -5 oC to +30 oC and scale length 12 mm/oC)

–

thermometer for the pipe wall of exposed pipe segments with a scale division of 0.1 oC (recommended scale length 12 mm/oC)

–

thermometer for filled water.

For the measuring of the temperature at the wall of the pipe it is as a rule sufficient to place one thermometer at every 2.5 km of the tested section. However, regardless of the length of the test section at least three thermometers should be used. –

for checks to ensure air-free condition (purge tests):

–

suitable measuring equipment to determine the amount of water drained from the pipe (such as a decimal balance and vessel; measuring vessel with sufficient cubic content).

After filling and purging (cf. Section 2.3) the test pressure is increased at a maximum rate of 3 bar/min and maintained as a rule for 24 hours after the temperatures have equalized. All values measured during this period should be recorded. It is recommended to ascertain that the line is airfree before beginning with the test. As far as the pipe wall temperatures in the buried portion of the tested section are concerned, it is normally sufficient to read the thermometer every 6 hours. All other measured values should be recorded every hour. The holding period/measuring time may be reduced, provided that the metrological requirements have been met, that the pressure follows the course of the temperature changes and that therefore the changes in volume exhibit a corresponding trend. After the holding period is over, the absence of air in the pipeline must be double-checked (purge test). For this purpose the pressure should be

lowered at least twice. Only the amount of water drained at the very end of the test and the corresponding reduction in pressure must be used as the basis for evaluation.

Calculation Symbols V

=

change in volume

in l

Vh

=

change in volume per hour

in l/h

VA

=

calculated amount drained

in l

VAB

=

actual amount drained

in l

Vri

=

volume of test section with pipeline radius ri

in m3

ri

=

internal pipeline diameter

in mm

s

=

actual wall thickness

in mm

A

=

calculation coefficient according to diagram 1 =

10-6 · bar-1

B

=

calculation coefficient according to diagram 2 =

10-6 · K-1

The calculation coefficients stated above apply to: coefficient of expansion

β = 11,1 · 10-6

in K-1

Young’s modulus (steel)

E = 206000

in N/mm2

transverse contraction

µ = 0,3

p

=

overpressure in pipeline

in bar

T

=

mean pipe wall temperature

in oC

L

=

length of pipeline

in m

Indices 1

=

at the beginning of test

2

=

at the end of test

x,y,ges

=

section lengths or thicknesses

0,89

=

constant coefficient of pressure changes in 10-6 · bar-1

Formulae The amount of water which has actually been drained is compared with the calculated amount by applying the formula below:

For different wall thicknesses and pipe radii, for the quotient

the proportional value of the volumes and wall thicknesses is determined as follows:

The calculated amount of water and amount of water actually drained may deviate from one another due to minor air entrapments, pipe grades, wall thickness and diameter tolerances. In order to obtain an analytic result which is sufficiently accurate, the rate of deviation should not exceed 6% and it should be included in the calculation as the ratio

in formula (3).

If there is no deviation,

becomes The change in volume of the tested pipeline section can be determined with the following state equiation.

If there are different wall thicknesses and pipe radii, formula (2) should be inserted correspondingly into formula (3).

Evaluation In the majority of cases the measuring tolerances of this method results in changes in volume, which in their summation do not cancel each other out and which can be converted by inserting all tolerances into the corresponding calculation formulae. To determine the allowable hourly change in volume therefore, the simplified formula given below must be applied which will yield a sufficiently accurate result:

Here the following limit values apply: a)

b)

c)

for line diameters da > 500 mm, if during pressure testing of all pipies a hoop stress of at least 87 % of strength parameter K in relation to minimum wall thickness was applied:

for line diameters da 500 mm, if during pressure testing a hoop stress of at least 87 % of strength parameter K in relation to minimum wall thickness was not applied on all pipes and for line diameters da < 500 mm

for lines with girth welds welded with a single pass:

3.2.2 Hydrostatic pressure testing (dual pressurization) – Method B2 After having applied the test pressure according to method B 1 and a holding time of 60 minutes, the test pressure must be lowered if possible to the point where the pressure at the high point of the line is at least 2 bar. The line is then repressurized until the test pressure is reached. As a rule, this pressure must be maintained for 24 hours. The measuring time may be reduced if the metrological conditions and the pressure over time correspond to the changes in temperatures, i.e. the changes in volume must exhibit a constant trend. During this period all measured values must be recorded. As far as the pipe wall temperatures in the buried portion of the tested section are concerned, it is normally sufficient to read the thermometer every 6 hours. All other measured values should be recorded every hour. After the holding period is over, the absence of air in the pipeline must be double-checked. For this purpose, the pressure should be lowered at least twice. Regarding the measuring apparatus, the evaluation of the test and the control check to ensure that the lines are free of air, Section 3.2.1 (pressure test method B 1 ) must be applied.

3.2.3

Pressure testing with air – Method B 3

3.2.3.1

General

The test pressure must be 1.1 times the maximum allowable operating pressure, but be at least 2 bar higher than the maximum allowable operating pressure. These test methods are applied on pipelines which are if possible completely buried. If possible, valves and mechanical joints should be

accessible. While the measurements are being carried out, the pressure in the pipeline should be recorded by a recording manometer. The measuring devices used must be a Class 1 recording manometer as well as Class 0.6 manometer and should have measuring ranges amounting to 1.5 times the testing pressure. After having applied the test pressure (maximum rate of pressure increase 3 bar/min) and once the target test pressure has been reached, the measurements begin. As reference value for temperature equalization after the injection of air, a duration of one hour can be assumed for 1 bar in test pressure, unless the equalization period can be curtailed by suitable measures (such as a compressor with cooling system). The potential influence of the measuring line on the measuring results should be kept to a minimum.

The following only applies to pressure measuring method B 3.2 and to the differential pressure measuring methods C 3.1 and 3.2 In order to ensure that a variation in pressure can be identified within an reasonable period of time, the length of the pipe sections to be tested should, if possible, not exceed the standard values stated below: DN

Length (km) up to 200

9,0

above 200

up to 300

6,0

above 300

up to 400

4,5

above 400

up to 500

3,5

above 500

up to 600

3,0

above 600

up to 700

2,5

above 700

2,0

The pressures and temperatures must be recorded during measuring. The intervals between and duration of the measurements must be defined in accordance with the pressure survey. If there are compelling reasons why part of the section of a line to be tested cannot be completely buried, the temperatures must be measured separately and taken into account in the calculation. For the measuring of the air temperature in the line, the soil temperatures at the pipeline should be measured at at least 2 locations while taking the local conditions into account. The soil temperatures at the line and at the test bottle should be established with thermometers with a scale division of 0.05 oC, the temperatures of the air and the pipe wall at exposed sections of the pipeline with thermometers with a scale division of 0.1 oC. If other measuring devices are used, such as a resistance thermometer, for example, these should guarantee the same measuring accuracy. The change in pressure p determined after the temperature influences have been taken into account must not exceed the absolute value stipulated below:

The symbols mean: pzul

=

maximum change in pressure

DN

=

nominal width

h

=

duration of measurement in hours

It is recommended to make control calculations during the measurement period in order to obtain information regarding the performance of the line with respect to tightness as early as possible. If at the end of the testing period used for the evaluation

p < pzul, the line is assumed to be tight.

The following shall only apply to pressure testing method B 3.2 and differential pressure measuring method C 3.2 For pressure-maintaining devices (such as deadweight pressure testers) a test certificate must have been obtained from the calibration authority or from the Physikalisch-Technische Bundesanstalt (PTB) [national metrology institute providing scientific and technical services]. The

temperature compensation must have an accuracy of 0.1 oC. As a minimum, the pressure-maintaining device must be capable of clearly indicating a pressure change of only 1 mbar. For the measuring of atmospheric pressure a barometer with a measuring accuracy of 1 mbar must be used.

3.2.3.2 Simplified pressure measuring – Method B 3.1 For buried lines, the holding time must be based on the relevant provisions contained in the Technical Rules of the DVGW; the holding time for exposed lines should be at least 2 hours. A pressure decrease as specified in the relevant provisions of the DVGW Technical Rules at the pressure recording manometer during the holding period is acceptable provided that temperature conditions are taken into account.

3.2.3.3 Pressure measuring with precision measuring equipment (such as deadweight pressure testers) - Method B 3.2 The tightness test must be evaluated on the basis of the pressure in the lines while the test is being carried out. The interface between the pressure oil contained in the measuring device and the air must be rendered visible by suitable means (e.g. by a level indicator).

Evaluation The actual pressure drop is calculated by applying the formula below:

Symbols p

=

Pressure change

t

=

temperature at the pipeline or test bottle, mean value of all temperatures measured simultaneously (oC), including the sections of the line allocable to them

p

=

absolute pressure

in mbar

pamb

=

atmospheric pressure

in mbar

p'

=

test pressure

in mbar

T

=

absolute temperature

in oK

T

=

273,15 + t degree Kelvin

index 1:

=

beginning

index 2:

=

end

index 3:

=

at the line

3.3

Differential pressure measuring with air - Method C 3

3.3.1

General

test period used as basis for evaluation

The tightness test must be carried out by determining the pressure difference between the line pressure and the pressure of a reference device (such as a test bottle or a deadweight pressure tester) while taking temperature changes into account. Furthermore, Section 3.2.3.1 must be applied.

3.3.2 Differential pressure measuring with test bottle - Method C 3.1 The measurements must be evaluated within a temperature range in which the outdoor temperature follows the same trend at the beginning and at the end of measuring; i.e. the beginning and end points of the evaluation should either rest on a rising or falling line section of the temperature curve. If the outdoor temperatures at the beginning and at the end of the pressure test are not identical, the impact of this temperature difference on the exposed sections of the pipeline must be taken into account in the calculation. For the measuring of differential pressure, instruments must be used which as a minimum must be capable of clearly indicating a pressure change

of only 1 mbar. The pressure change is calculated according to the isochoric equation-of-state by applying the formula:

Symbols (cf. legend to formula (6)): U

=

pressure difference between line pressure and pressure in bottle; measured at the differential pressure gauge in mbar

p

=

(p' + pamb)

in mbar

Index F: at the bottle.

3.3.3 Differential pressure measuring with pressure-maintaining device – Method C 3.2 As differential pressure gauge a device which can be pressurized from one side, such as a Barton cell or electric measuring transducer, must be used. The counter-pressure at the pressure maintaining device must be set to the line pressure when beginning with the measurements and must not be changed during the measurement period. Any temperature dependencies must be taken into account. The pressure drop is calculated with the formula:

Symbols: see legend below formulae (6) + (7).

3.4 Pressure measuring-/volumetric test - Method D Pressure measuring-/volumetric test (dual pressurization) - Method D2 Pressure measuring/volumetric methods are hydrostatic pressure tests during which pipes and pipe bends are pressurized up to the yield point of the pipes taking the allowable integral plastic deformation of the pipeline into account. This method must be carried out in accordance with VdTÜV-Merkblatt Rohrleitungen 1060 .

4

Regulations and Technical Rules

4.1

Accident prevention regulations

UVV-VBG 1

General provisions

UVV-VBG 50

Works on gas pipelines

Source:

Carl Heymanns Verlag KG, Luxemburger Str. 449, 5000 Köln 41

4.2 DVGW-System of Rules DVGW-Code of Practice G 260/I

Gas quality

DVGW-Code of Practice G 458

Subsequent pressure increase in gas lines

DVGW-Code of Practice G 459

Gas service lines for operating pressures up to 4 bar - Construction

DVGW-Code of Practice G 461/I

Installation of gas lines with operating pressures of up to 4 bar with pressure pipes and ductile castiron pipe fittings

DVGW-Code of Practice G 461/II

Installation of gas lines with operating pressures above 4 bar to 16 bar with pressure pipes and ductile cast-iron pipe fittings

DVGW-Code of Practice G 462/I DVGW-Code of Practice G 462/II

Steel gas pipelines for operating pressures up to 4 bar - Pipes and fittings Steel gas pipelines for operating pressures above 4 bar to 16 bar - Construction

DVGW-Code of Practice G 463

Construction of steel gas pipelines for operating pressures above 16 bar

DVGW-Code of Practice G 465/II

Work on gas pipeline networks with an operating pressure up to 4 bar

DVGW-Code of Practice G 466/I

Gas pipe systems made of steel pipes with an operating pressure above 4 bar; maintenance

DVGW-Code of Practice G 466/II

Gas pipe systems of ductile cast-iron with operating pressures above 4 bar to 16 bar - Maintenance

DVGW-Code of Practice G 472

Laying of pipelines made of non-plasticized PVC (non-plasticized polyvinyl chloride) for operating overpressures of up to 1 bar and of non-plasticized PE (non-plasticized polyethylene) for operating overpressures of up to 4 bar for gas pipelines Technical rules on the construction and equipping of gas pressure regulating stations with inlet pressures of above 100 mbar up to and including 4 bar

DVGW-Code of Practice G 490 DVGW-Code of Practice G 491

Gas pressure regulating stations for inlet pressures up to and including 100 bar Planning, production, construction, testing, commissioning and operation

DVGW-Code of Practice G492/II

Construction and equipping of gas flow measurement systems with a standard flow rate of at least 3000 m³/h and an overpressure of more than 4 bar; bulk flow metering

DVGW-Code of Practice G 496

Pipelines in gas installations

DVGW-Code of Practice G 497

Compressor stations on gas transmission pipelines

DVGW-Code of Practice G 498

Transmission pressure vessels in gas pipelines and systems of the public gas supply - Production, installation, commissioning and operation Technical rules on gas installations (DVGW-TRGI'86)

DVGW-Code of Practice G 600 Source:

ZfGW-Verlag GmbH, Postfach 90 10 80, Voltastraße 79, 6000 Frankfurt/Main 90

4.3 DIN-Standards DIN 1304-1 01.84

Letter symbols for physical quantities; symbols for general use

DIN 2401-1 05.77

Internally or externally pressurized components, pressure and temperature specifications, nominal pressure stages

DIN 2402 02.76

Pipelines, nominal widths, definition, classification

DIN 2470-1 02.77

Steel gas pipelines for permissible working pressures up to 16 bar; pipes and fittings

DIN 2470-2 05.83

Steel gas pipelines for maximum operating pressures up to 16 bar; pipes and fittings

DIN 3230-5 08.84 DIN 30690-1 07.83

Technical delivery conditions; valves for gas installations and gas pipelines; requirements and testing Construction elements in the gas supply system - Part 1: Requirements for construction elements in gas supply systems

DIN 50104 11.83

Testing of hollow bodies by internal pressure; leak detection up to a certain pressure value; general specifications

Source:

Beuth Verlag GmbH, Burggrafenstraße 4-7, 1000 Berlin 30 oder ZfGW-Verlag GmbH, Voltastraße 79, 6000 Frankfurt/Main 90

4.4 VdTÜV-Merkblätter VdTÜV-Merkblatt Rohrleitungen 1060 08.77 Source:

Appendix Diagram 1

Richtlinien für die Durchführung des Stresstest [Stress testing guidelines]

Verlag TÜV Rheinland, Am Grauen Stein, 5000 Köln 91

Calculation coefficient A

Diagram 2

Calculation coefficient B