pars oil & gas company - pogc testing pr90pogc001.pdf · pars oil & gas company gas testing...

Pars Oil & Gas Company

Gas Testing Safety Procedure

HEALTH, SAFETY AND ENVIRONMENT PROCEDURE


DOCUMENT ID - PR-90-POGC-001 REVISION ‐ 0.0



Pages

17

Revision 00

Document ID.

PR-90-POGC-001

HSE Department


Document Authorization

Document Type

Security Classification

Document

Authority/Owner

Document Custodian

Safety Procedure Unrestricted P.O.G.C HSE

Document Author Approved By

HSE-S564392 M.Ansari

HSE-S593443

PARS OIL & GAS COMPANY

September 2012- Gas Testing Safety Procedure Page 2

Table of contents

1. INTRODUCTION .................................................... .................................................................3

2. PURPOSE .................................................................................................................................. 3

3. SCOPE........................................................................................................................................ 3

4. RESPONSIBILITIES ............................................................................................................... 3

5. PROCEDURES ......................................................................................................................... 5

5.1 GENERAL ................................................................................................................................... 5

5.2 COMBUSTIBLE GASES ................................................................................................................ 7

5.3 TOXIC AND SUFFOCATING GASES................................................................................................ 9

5.4 OXYGEN DEFICIENCY :............................................................................................................. 10

6. DEFINITION AND ABBREVIATIONS : ............................................................................ 11

7. REFERENCE .......................................................................................................................... 11

8. FIGURES AND APPENDIXES ............................................................................................. 12

SUGGESTION FORM



1. INTRODUCTION

Pars Oil and Gas Company (POGC), a subsidiary of National Iranian Oil Company (NIOC),

was established in 1998. POGC is a developmental and manufacturing organization that

specializes in the fields of engineering and management of development projects, production,

operation and integrated management of oil and gas reservoirs. POGC’s mission is to ensure

sustainable and preservative production and development of Iran’s oil and gas industry in the

areas under its responsibility, development of oil and gas value chain as well as optimization

of energy supply processes at national, regional and international levels. POGC is also in

charge of development of joint and non-joint oil and gas fields of the country including South

Pars, North Pars, Golshan and Ferdowsi.

Aimed at creating superior value and boosting the level of satisfaction of the beneficiaries

and with an approach focusing on sustainable, integrated and knowledge-oriented production

and development, the company feels committed to comply with national and international

requirements, regulations and standards in such areas as quality, safety, as well as

occupational and environmental health.

2. PURPOSE

The purpose of this procedure is to assist in ensuring the safety of personnel and the plant

from the hazards of:

• Toxic and combustible gases

• Oxygen deficiency / enrichment.

3. SCOPE

This procedure is applicable for protect all employees in POGC projects from the hazards

of gases, fumes, vapors and where Hydrocarbons, oil and gas are produced or treated and

where presence of Toxic and combustible gases and Oxygen deficiency / enrichment

possibility has been proven by the safe method of gas testing .

4. RESPONSIBILITIES

4.1 Site Manager

The Site Manager is responsible:

• To ensure that the work is carried out as per this present document, where

necessary.

• To ensure that a system is in place to train and to evaluate the competency of the

designated gas testers.



• To provide sufficient signs, barriers and flashing lights as appropriate to the area

covered.

• Provision of instruction with regard to the hazards and arrangements in place.

• To provide sufficient numbers of compatible and approved gas detection equipment

on site.

• Planning the work, as far as practicable, to include contingency plans and

arrangements.

• Adequate calibration and test equipment, with spare parts that can be fitted on site.

• Sufficient numbers of escape equipment as required by the numbers of persons who

may be exposed.

4.2 HSE Manager

The HSE Manager is responsible for:

• Monitoring the safety of all working practices.

• Custody of portable gas detection equipment and the training of the site designated

gas testers.

• Ensuring that all necessary tests are carried out as required by the Work site

condition and as stated by the permit to work system upon completion of a specific

risk assessment.

• Ensuring that Supervision and Subcontractor management are familiar with this

procedure and that all persons concerned are trained as well.

• For ensuring that all the necessary gas checks have been identified and carried out

prior to the issue of relevant Work Permits.

• Monitoring site conditions and ensuring that persons who may be affected by this

procedure are aware of the hazards and precautions to be taken.

• Arrange for the necessary training of personnel for testing, calibration and

maintenance of records.

• Updating this procedure as necessary.

• Ensuring that when occasions requiring work in areas affected by toxic and

combustible gases and oxygen deficiency / enrichment possibility, necessary

precautions are in place as per work permit requirements.

• For ensuring that routine calibration checks of all portable gas detectors are carried

out in accordance with the manufacturers’ instructions.

4.3 HSE Supervisor

HSE Supervisor is responsible for:

• Monitoring the safety of all working practices.

• ensuring that work area is free of any dangerous gas.

• providing all PPE needed for carry out the job.

4.4 Task Supervisor

Task Supervisor is responsible to provide a safe work place and work situation for

workers and before entry to any confined space gas testing should be carry out.



Task Supervisor is responsible to provide the work permit according to the work is

going to carry out.

4.5 Commissioning Manager

• Ensuring that all persons working are aware of, and comply with the relevant points

from this Safety Procedure.

4.6 Field Supervisor(for commissioning & production)

The Field Supervisor is responsible for:

• Ensuring that all procedures and safeguards are fully implemented.

• Preparation of the work-site to ensure that activities will be conducted safely.

• Providing trained Stand-By Men whenever required.

4.7 Safety supervisor and Safety Engineer (for commissioning & production )

The Safety supervisor and Safety Engineer are responsible for:

• Monitoring the safety of all working practices all over the gas plant.

• Custody of portable gas detection equipment and the training of personnel in its use.

• Ensuring that all necessary gas tests are carried out by AGT as required by the Work

Permit System.

4.8 Head of Maintenance (for commissioning & production )

The Head of Maintenance is responsible for ensuring that routine calibration checks of all

portable gas detectors are carried out in accordance with the manufacturers’ instructions.

4.9 Qualified Person

This person should be able to identify the hazards workers may face in the space and be

familiar with instruments and procedures to test for oxygen levels, flammability, and

exceeded limits of air contaminants or toxic substances.

Before allowing worker entry, it should be tested from the outside to determine whether

the space atmosphere is safe. The qualified person should decide on the necessary tools

for safe work in the confined space.

5. PROCEDURE

5.1 General

Gas testing in this procedure refers to portable gas detection, not fixed gas detection. These

procedures supplement the manufacturers’ procedures: they do not replace them.

The importance of gas testing for flammable gas, toxic vapors and gases, and oxygen

deficiency cannot be over-emphasized.

Personnel who carry out gas testing as authorized gas testers (AGT) must be thoroughly

trained in the use of gas testing equipment and the significance of the results. Before using

any gas testing equipment it should be checked according to the check procedure in the



manufacturers’ manuals. It may include battery check, Filter Check, Probe check and

Calibration check.

Portable detectors are used to supplement the fixed detection systems and must be used

before the issuance of the relevant work permit. Care must be taken around valve spindles,

flanges, drains and in floor voids. Probes should be used to reach inaccessible places. AGT

must be careful to prevent any moisture of sludge enter through the probe hose.

Warning: A particular attention should be given to areas adjacent to the work site which

conditions could be altered by the work in hands (particularly temperature

increase), since sludges and deposits might be starting to evaporate and to create

an explosive / toxic atmosphere only after a certain period of time.

Prior to beginning work, you should determine whether the materials you will work

with pose any special hazards, such as being pyrophoric. Pyrophoric substances

ignite spontaneously in air at room temperature, either by oxidation or by reaction

with atmospheric moisture.

The atmosphere must be sampled at the following places:

• In the actual work area

• In areas in which products of the work may fall (e.g. welding slag, sparks, etc.)

• In areas which may be affected by the work (e.g. inside a tank if welding work is to

be performed on the outside and therefore cause high surface temperatures, etc.)

When testing inside vessels, remember that some toxic gases are heavier than air and that

gases can be released when sludge is disturbed. Before allowing a vessel to be entered, the

vessel entry procedure must be followed.

These procedures set down the general conditions for the instruments provided for:

• Indication of the presence of toxic or flammable gases

• Indication of oxygen deficiency or enrichment

• Measurement of the concentration of selected gases

• Monitoring the atmosphere to provide a warning of the presence of toxic or

combustible gases.

All meters and instruments must be EX rated as intrinsically safe. They are suitable for use

with all saturated hydrocarbon gas and Hydrogen but not for Acetylene for which specific

equipment is required. They should also show an in date calibration tag and should be

identified by a unique Identification Number.

The principles for safe and accurate gas testing might be summarized as followed:

• Gas testing personnel must be fully trained in all aspects of gas testing. Competency

assessment to be set up before Gas Testers nomination.

• Gas testing equipment must be regularly maintained.

• Tests must be carried out prior to, during and after the issue of a Permit to Work.

• Gas monitors should be checked for sample using calibration sample gas prior to

use each shift.

• Any atmosphere being sampled must be approached as if it is flammable and/or

toxic and due precautions taken.



• The possibility of oxygen deficiency or enrichment must also be considered.

• Care must be taken to ensure that tests are representative of the atmosphere and that

results are reproducible. It is not sufficient to rely on a sample taken from only one

point since pockets and layers of varying gas concentration may exist.

• Prior to gas testing:

Check that the plant is operating under the desired conditions and note any

special conditions

Select the sampling positions

Select the apparatus to be used

Determine the duration and the periodicity of sampling.

The method and equipment used for gas tests must be selected with regard to the nature of

the atmosphere likely to be present.

5.2 Combustible Gases

5.2.1 Maximum permissible concentration

The explosive, or flammability limits of gases and vapors, are normally expressed as a

volume percentage range between Lower Explosive Limits (LEL) and Upper Explosive

Limits (UEL). These levels vary for different compounds and it is the Lower Explosive

Limit (LEL) that is used as a basis for the combustible gas test. The table below lists the

LEL and UEL of some relevant gases:

GAS LEL % UEL %

Methane

Ethane

Butane

Pentane

Propane

Hydrogen

hydrogen sulfide

Acetylene

Ammonia

5.30

3.00

1.86

1.30

2.10

4.00

4.30

2.50

15.00

13.30

15.50

8.41

7.80

9.30

74.20

46.00

82.00

28.00

For example, in an atmosphere containing Methane, a reading of 10 % LEL on the

explosimeter dial indicates that the actual concentration in the air is 10 % of 5.3 = 0.53 %

by volume. (See Figure 1 of this procedure.)

Note that an explosimeter needs sufficient range of oxygen to give a true reading (more

than 15% Volume).Unless otherwise stated in manufactures’ manual; Explosimeter to

measure the % of LEL do not work correctly when the atmosphere contains less than 15%



Oxygen. Before opening a vessel or pipe work to the atmosphere always ensure it is free

from gases and hydrocarbon content.

In case of O2 deficiency (less than 15%) such as gas freeing activities, gas testing shall be

performed by Infra Red (IR) combustible gas detectors.

Before gas testing of any pipeline, vessel or equipment , it is required to know about the

fluid of that pipeline or equipment then to know about density of the specified gas which

needs to be checked by gas testing.

(See appendix 1 of this procedure)

5.2.2 Combustible Gas Detectors

Combustible gas tests must be carried out using only gas detectors suitably calibrated for

use with hydrogen and/or hydrocarbon gas mixtures. Meter readings are given as a

percentage of the LEL of the combustible gas and it is the result which must be specified in

the appropriate space of the Work Permit. Sludge or scale, within a vessel, gives off vapor

when disturbed and/or heated, this fact must be borne in mind when testing for gas in a

confined space to determine the suitability for entry.

Before and after each series of tests, or up to a maximum of two hours continuous use, the

meter must be checked for minimum response, following the procedure in the instruction

manual.

Information and results from detectors must be reported to the Safety supervisor /Safety

Engineer.

Oils heavier than kerosene do not give off sufficient vapors at ambient temperature to be

detected. Work places must, therefore always be visually inspected for the presence of such

oils, and if present, they must be removed, or blanketed, to the satisfaction of

Production/Site Superintendent and the Safety Authority. Information and results from

detectors and any gas chromatography analysis must be reported to the person in charge of

the installation and the Safety Authority for assessment.

Water, or liquid hydrocarbons, must not be allowed to enter the instrument. When testing

sumps or equipment where liquid could be present, a liquid trap must be fitted to the

sample line.

Warning: The calibration gas used should be as closed as possible from the potentially

explosive atmosphere monitored. Particularly the reading of the explosimeter

when sampling condensates vapors might be over optimistic if methane is

used as calibration gas (which is generally the case in gas processing plant).

5.2.3 Continuous monitors

There are various instruments available for the continuous monitoring of combustible gas

atmosphere. Some instruments are designed as free-standing, self-powered units fitted with

a portable diffusion head and flammable gas and vapor detectors. They are used with an

alarm system.



Gas concentrations up to 100 % LEL are indicated on a meter and the alarm is a penetrating

audio signal, coupled with a flashing lamp. The level at which the alarm operates can be

pre-set by internal adjustment.

The monitor can be used for spot sampling with the addition of an aspirator.

By the addition of an aspirator the monitor can be used for spot sampling.

Warning: Combustible gas detectors are designated to detect gas in AIR. It is not

possible for the instrument to give an accurate LEL reading in a steam, inert or

oxygen deficient / enriched atmosphere.

Special equipment ("Tank safe" monitor) or chemical detector tubes shall be

used in such cases.

5.3 Toxic and suffocating gases

5.3.1 Maximum permissible concentration

The toxic gases most likely to be encountered are Hydrogen Sulfide (H2S) and Carbon Monoxide (CO). The maximum concentrations of these toxic gases for entry are as follows:

MAXIMUM CONCENTRATIONS OF TOXIC GAS (PPM) FOR ENTRY

Gas

Entry without

Breathing

Apparatus

Entry With

Suitable

Breathing

Apparatus

No Entry

Purge and

Retest

Hydrogen Sulfide (H2S)

Carbon Monoxide (CO)

< 1 ppm

< 1 ppm

1 to 20 ppm

1 to 250 ppm

> 20 ppm

> 250 ppm

There are two methods used for the detection of toxic gases:

• Portable Detectors, used for continuous monitoring.

• Detector Tubes, used to measure the concentration in a spot test.

H2S is heavier than air so may concentrate in lower areas; it is resolvable in water or sludge,

so it is essential to empty the vessels and containers before any entry to, or hot work

activities

5.3.1.1 Portable detectors (continuous monitoring) Some types of portable detectors allow the monitoring of hydrogen, carbon monoxide or

sulfur dioxide content in the range 0 - 200 ppm by means of interchangeable sensor heads.

The instrument gives audible and visual alarms, which are adjustable throughout the

measuring range.



There are two levels of alarm that produce different tones and visual LED indication for the

Long Term Exposure Limit (LTEL) and Short Term Exposure Limit (STEL) values of the

toxic gas being measured. The concentration is displayed on a meter in ppm.

5.3.1.2 Detector Tubes (Spot Tests)

The concentration of a specific toxic gas can be determined by measuring the length of the

stain produced in a chemically filled tube into which a measured volume of sample gas is

drawn, under pre-determined conditions.

Detector tubes are available for the various toxic gases likely to be present during

operations. For the correct operating procedures refer to the manufacturers’ manuals.

5.4 Oxygen Deficiency :

Before entering a vessel or enclosed space, tests of the oxygen content of the atmosphere

must be made.

Tests must also be carried out whenever there is any doubt as to purity of the air within a

vessel.

Internal rusting of the metal in a closed empty tank, which has been unused for some time,

may cause oxygen deficiency.

Oxygen deficiency tests are carried out by:

• Oxygen Monitors - continuous checking.

• Multi-gas Detectors - spot checks.

Clearance to enter a vessel or confined space without wearing breathing apparatus is only

given when the concentration of oxygen in the atmosphere is in acceptable level.

Acceptable level an atmospheric oxygen concentration is 20.9 percent. Although the OSHA

recommended Oxygen level for entry is between %20 to %23 but we must think that reduce

or enhance of oxygen may be reason for presence of toxic gas or other chemical reaction.

It would better to consider these items:

Notice, NO-1: National Iranian Oil Company (N.I.O.C.) safety regulations that concern to

this procedure PART 7: Work permit, sections: Gas testing, Responsibilities.

Notice, NO-2: All gas detectors and their equipments should be explosion proof (EX) and

conform to Iranian Petroleum Standards, IPS: E- EL-110. IPS: G- SF-110.



6. Definition and abbreviations :

Threshold limit value-short-term exposure limits (TLV-STEL):

15-minute exposure limit that should not occur more than 4 times during the workday.

Threshold limit value-time weighted average (TLV/TWA):

Average concentration limit for a normal 8-hour workday and a 40-hour workweek that

should not cause adverse effects.

Entry permit: A written document provided by the worker that specifies the conditions of

entry into a hazardous confined space.

Lower explosive limit (LEL): The minimum concentration of a particular combustible gas

or vapor necessary to support its combustion in air is defined as the Lower Explosive Limit

(LEL) for that gas. Below this level, the mixture is too “lean” to burn.

Upper explosive limit (UEL):The maximum concentration of a gas or vapor that will burn

in air is defined as the Upper Explosive Limit (UEL). Above this level, the mixture is too

“rich” to burn.

Immediately Dangerous to Life and Health (IDLH) Any condition that poses an immediate or delayed threat to life, and would cause

irreversible adverse health effects or interfere with an individual's ability to escape unaided

from a space. The IDLH also represents a maximum concentration from which, in the event

of respirator failure, a person could escape within 30 minutes without experiencing any

irreversible health effects.

Oxygen Deficiency : An atmosphere containing oxygen at a concentration of less than

19.5% by volume as measured by an oxygen measuring device.

Isolation :The process by which a permit required space is removed from service and

protected against the release of energy and material into the space.

PPM : Parts Per Million

I.S. : Intrinsically Safe equipments

I.R. Gas Detectors : Infra Red Gas Detectors which can detect combustible gases in O2

free spaces.

AGT : Authorized Gas Tester is a well trained and qualified person which knows the

method of gas testing and the behavior of the gases.

Gas Test: Is a careful exam by AGT using an appropriate gas tester to find out;

A) There are no toxic (poisonous) gasses present in the air, and that the atmosphere

is safe to breath.

B) There is sufficient Oxygen in the air to support life.

C) There are no explosive gasses, and so minimize the possibility of an explosion

happening

7. Reference 1. National Iranian Oil Company (N.I.O.C.) safety regulations PART 7: Work permit,

sections: Gas testing.

2. Iranian Petroleum Standards, IPS: E- EL-110 , IPS: E-SF-260

3. OSHA 29CFR1910.146



8. Figures and Appendixes

Figure 1: Explosive Range

Figure 2: Gas Behaviour

Appendix 1: Densities of Different Gases

Appendix 2: Gas Testing Check List



Figure 1: Explosive Range

Figure 2: Gas Behaviour



APPENDIX 1: DENSITY OF DIFFERENT GASES

GAS

Density (Air = 1)

Ammonia 0.6

Butane 2.1

Carbon Dioxide 1.5

Carbon Monoxide 0.97

Ethane 1.05

Ether (diethyl) 2.5

Ethylene 0.97

Ethylene Oxide 1.5

Formaldehyde 1.07

Hydrazine 1.1

Hydrogen 0.07

Hydrogen Cyanide (poison) 0.93

Hydrogen Sulphide (poison) 1.18

Methane 0.54

Mathanol 1.1

Methylamine 1.08

Nitric Oxide 1.04

Oxigen 1.1

Propane 1.55



APPENDIX 2: GAS TESTING CHECK LIST

No.

Description

Yes

No

N/A

Comments

1

Are personnel trained in the use of gas detector

equipment?

2

Are explosimeters only used when the level of oxygen

is sufficient i.e. > 15 %?

3

Are personnel aware of where to take sample readings?

4

Are oxygen monitors with alarms worn by personnel

who enter enclosed spaces?

5

Is a gas test performed before any hot work?

6

Is there a permanent gas detector (with alarms set at

25% LEL) when any hot work is performed within a

vessel or an enclosed space?

7

Has the correct permit been issued?

8

Are oxygen levels checked sufficiently often for work

in an enclosed space?

9

Are personnel aware of the dangers of oxygen

enrichment?

10

Is there any possibility of the presence of H2S or CO?

If so, is it being tested for?



SUGGESTIONS FOR THE POGC

GAS TESTING SAFETY PROCEDURE

MANAGER, HSE Department


Tehran I.R. Iran

Please consider the following suggestion(s) relative to the POGC Gas testing safety procedure:

(Signature)

(Date)

(Address)

Contact Telephone Number

Contact FAX Number

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