General Safety Procedures

GENERAL SAFETY PROCEDURES

HYDROGEN SULFIDE

GENERAL SAFETY PROCEDURES

HYDROGEN SULFIDE

Procedure Number: GSP-811

GENERAL SAFETY PROCEDURES

HYDROGEN SULFIDE

TABLE OF CONTENTS

HYDROGEN SULFIDE- GSP-811

1.0PURPOSE

2.0SCOPE

3.0DEFINITIONS

4.0PROPERTIES OF HYDROGEN SULFIDE

4.1.General Description

4.2.Flammability

4.3.Toxicity

4.4.Specific Gravity

5.0LOCATIONS WHERE H2S CAN BE PRESENT

6.0EQUIPMENT AVAILABLE FOR PROTECTION AGAINST H2S INHALATION

7.0TRAINING

GENERAL SAFETY PROCEDURES

HYDROGEN SULFIDE

1.0PURPOSE

The purpose of this procedure is to provide employees, and other personnel working at ValeroTerminaling and Distribution Company (Valero) facilities, with information on the harmful effects and proper safety and health precautions to be taken with equipment or material which may contain Hydrogen Sulfide.

2.0SCOPE

This procedure applies all personnel, company or contractor, working in or on Valero owned, operated or maintained pipelines or facilities.

This procedure covers the basic points in the protection of personnel from the harmful effects of hydrogen sulfide which has been designated as an Extremely Hazardous Substance (EHS). It is intended as a source of information and guide to be used in conjunction with specific operating procedures which address handling of potential H2S operations. Specific health and safety information should be obtained from the designated HSE representative.

3.0DEFINITIONS

Airline Respirator

An air supplying respirator in which the respirable gas is not designed to be carried by the wearer (also known as supplied air respirators).

Air-Purifying Respirator

A respirator in which ambient air is passed through an air purifying element that removes the contaminants(s). Air is passed through the air-purifying element by means of the breathing action or by a blower.

Air-Supplying Respirator

A class of respirators that supply a respirable atmosphere, independent of the workplace atmosphere.

Breakthrough

The penetration of a chemical vapor through filter cartridge. The quantity or extent of breakthrough during service life testing is often referred to as the percentage of the input concentration.

Cartridge

A container with a filter, sorbent, or catalyst, or a combination of these items, which removes specific contaminants from the air passed through the container.

Certified

Evaluated and listed as permissible by the National Institute for Occupational Safety (NIOSH), the Mine Safety and Health Administration (MSHA), or the Bureau of Mines (BM).

Contaminant

A harmful, irritating, or nuisance airborne material

Demand Respirator

An air-supplying respirator that admits respirable gas to the face piece only when a negative pressure is created inside the face piece by inhalation.

Designated HSE Representative

The designated HSE representative may be a Valero employee or group or it may be a contracted entity providing specialized services to assist in environmental, health, industrial hygiene, and safety compliance activities. Subject to corporate management approval, each facility may satisfy these responsibilities through a combination of in-house and outside contracted services.

Escape Respirator

A respirator intended only for use during emergency egress from an emergency situation or hazardous atmosphere.

Exposure Limit

The maximum allowable concentration of a contaminant in the air to which an individual may be exposed. These may be time-weighted averages, short-term limits, or ceiling limits.

Gas

A fluid that has neither independent shape nor volume and tends to expand indefinitely.

Hazardous Atmosphere

An atmosphere that contains a contaminant in excess of the exposure limit, explosive limit, or that is oxygen deficient.

Immediately Dangerous to Life or Health (IDLH)

Any atmosphere that poses an immediate hazard to life or poses immediate irreversible debilitating effects on health.

Negative Pressure Respirator

A respirator in which the air pressure inside the respiratory inlet covering is negative during inhalation with respect to the ambient air pressure.

Positive Pressure Respirator

A respirator in which the pressure inside the respiratory inlet covering is normally positive with respect to ambient air pressure.

Powered Air Purifying Respirator

An air-purifying respirator that uses a blower to force the ambient atmosphere through air-purifying elements to the inlet covering.

Pressure-Demand Respirator

A positive pressure air supplying respirator that admits respirable gas to the face piece when the positive pressure is reduced inside the face piece through inhalation.

Self-Contained Breathing Apparatus (SCBA)

An air-supplying respirator in which the respirable gas source is designed to be carried by the wearer.

Manager

The management representative with overall responsibility for the terminal, area, site or function

Supervisor or his Designated Representative

The management representative with immediate responsibility for the terminal, area, site or function

Time-Weighted Average

The average concentration of a contaminant in air during a specific time period.

Vapor

The gaseous phase of matter that normally exists in a liquid or solid state at room temperature.

4.0PROPERTIES OF HYDROGEN SULFIDE

Note:Review the MSDS for information regarding First Aid to be administered in the event of H2S contact or inhalation.

4.1.General Description

Hydrogen sulfide is a flammable, colorless gas and in low concentration has the foul odor of “rotten eggs.” The odor of hydrogen sulfide can serve as a good initial warning of its presence. However, at higher concentrations the olfactory system is affected and the sense of smell is lost.

4.2.Flammability

In mixtures between 4.3% and 46% by volume, it is explosive. A mixture of hydrogen sulfide and air can be ignited at 500ºF.

4.3.Toxicity

At less than 10 parts per million (PPM) in air, the gas has a distinct rotten egg odor. The odor of rotten eggs may be detectable at concentrations of 0.02 PPM or less. Ten PPM in air is the permissible exposure limit or the concentration in which a person can stay 8 hours without injury. The short term exposure limit (15 minutes) is 15 PPM.

Adequate ventilation and proper equipment isolation and preparation, are the most important considerations in keeping hydrogen sulfide concentration below the permissible exposure limit of 10 PPM. At 100 PPM, the sense of smell is deadened in a few minutes, which may give the person the feeling that the presence of gas has disappeared when in reality the concentration may have increased. Therefore, THE SENSE OF SMELL IS NOT RELIABLE FOR DETECTING THE CONCENTRATION OF HYDROGEN SULFIDE.

Concentrations of 300-1000 PPM cause rapid unconsciousness and death through respiratory paralysis. It is associated with an unusual diversity of symptoms including chronic keratoconjunctivitis, nausea, insomnia, pulmonary edema, balance disorders, polyneuritis, and gray-green discoloration of teeth.

It is important that a person entering the contaminated area to make a rescue be equipped with an independent source of breathing air.

4.4.Specific Gravity

The gas has a molecular weight of 34 which makes it slightly heavier than air. This may cause it to settle in depressions and excavations.

5.0LOCATIONS WHERE H2S CAN BE PRESENT

The presence of hydrogen sulfide gas is and should be identified at all Valero operations by posting signs. Some operating units may contain, or have the potential to contain, some concentration of the gas. In addition the gas may be found in storage tanks, slop systems, sewers, separators, etc. Signs are normally posted when the potential for H2S exists.

6.0EQUIPMENT AVAILABLE FOR PROTECTION AGAINST H2S INHALATION

Note: Air Monitoring must be conducted in all operations where H2S potential is present. Contact the Industrial Hygiene or HSE Representative for information.

Breathing air equipment must be the pressure-demand type. This type maintains a positive pressure on the face mask. Two types are available.

a. Thirty or 60 minute self-contained breathing apparatus (SCBA).

b. Supplied air breathing equipment such as a breathing air quality system supplied Air Line which is designed for longer periods with escape bottle.

Note refer to the Respiratory Procedure GSP-602

OPERATIONS WHERE BREATHING AIR EQUIPMENT MUST BE WORN

Rescue purposes in H2S atmosphere.

When sampling, gauging, drawing water, or blanking sour stock equipment.

Working in sour stock pipe trenches or excavations.

Blanking flare lines or opening flare equipment.

When opening any lines and equipment handling sour stock.

When required by permit instructions.

OPERATIONS WHERE BREATHING AIR EQUIPMENT SHOULD BE CONSIDERED

 When going inside firewalls of sour stock tanks.

 When working near sewers or in trenches or excavations where H2S might collect.

 Testing for H2S until instruments determine that the concentration is not hazardous.

7.0TRAINING

Hydrogen Sulfide training must be conducted and include these procedures and “operation specific” H2S procedures and information. Training must be provided to:

All employees and personnel working with hydrogen sulfide containing equipment or materials.

Emergency rescue personnel for locations with the potential for H2S emergencies.

Personnel responsible for the monitoring or measurement of H2S containing equipment or material.

Note:See also ANSI 2390 – Accepted Practices for H2S Safety Training Programs