OCHS2420 Mod7 Hydrogen Sulphide

Question 1

Describe the health effects of inhalation of hydrogen sulphide.

Answer 1

Odor.

Irritation - eyes, nose, mouth, throat, lung. Loss of appetite.

Loss of smell

Headache, dizziness, ataxia, collapse.

Respiratory paralysis, cardiac arrhythmia, death.

Question 2

How H2S is formed?

Answer 2

1, organic material
2, anaerobic conditions
3, sulphate-reducing bacteria
= H2S

Question 3

Explain the role of OHS regulators and energy boards in regulating worker exposure to hydrogen sulphide

Answer 3

H2S is covered by broad hazardous material OHS laws, and a few specific H2S regulations in known high-risk industrial activities (oil & gas).

National and provincial energy board regulators, in their activities to protect public safety, indirectly improve worker safety.

Note:

• BC Oil and Gas Commission
• Canada Energy Regulator

Question 4

What is hydrogen sulphide?

Answer 4

H2S
Usually a gas (unless under high pressure or extreme cold)
Highly toxic
In tiny amounts, has a rotten egg/sulphur smell

H2S is typically a by-product of other processes
H2S is created by anaerobic decomposition of organic material

Rapidly dissolves in water (or mucus membranes) to produce sulphuric acid.

Question 5

What is sour gas?

Answer 5

Natural gas mixed with H2S.

The natural gas industry processes sour gas to remove H2S.

Question 6

What is the usual H2S ceiling?

Answer 6

The ceiling limit for hydrogen sulphide is 10 parts per million.
C 10 ppm

No worker, at any time, for any duration, may be exposed to more than 10 ppm.

Question 7

What is the H2S IDLH?

Answer 7

The Immediately Dangerous to Life or Health limit for hydrogen sulphide is ~100 ppm

Question 8

What are the health effects of hydrogen sulphide?

Answer 8

Inhalation:
Airway irritation, pulmonary edema, headache, respiratory paralysis, unconsciousness, death.
Long term effects may cause asthma, RADS (reactive airway dysfunction syndrome), nervous system dysfunction.

Skin contact:
Cold effects from liquid form.

Eye contact:
Irritant. Cold effects from liquid form.

Not known to be carcinogenic, teratogenic, embryotoxic, reproductive toxin, mutagenic.

Question 9

What is the rule of thumb for H2S concentrations?

Answer 9

1-10-100-1000ppm

1= Smell
10= Irritation (Regulatory limit)
100= Severe nose/throat/lung irritation, loss of appetite (severe enough to prevent self-rescue)
1000= Respiratory paralysis, arrhythmia, death

(around 150ppm, sense of smell stops working)

Question 10

What workplaces may have H2S? (Name 4/7)

Answer 10

Gas plants, refinaries, petro-chemical plants, sulphur recovery plants.

Underground mines

Tank cars (railway), tank trucks (road)

Commercial laboratories

Septic tanks, sewers, manure handling areas

Pulp & paper mills

Pipelines

Question 11

What is the LEL? (context, fire risk)

Answer 11

LEL = Lower Explosive Limit

The lowest concentration (%) of a gas or vapour in air capable of producing a flash of fire in presence of an ignition source (arc, flame, heat).
Sometimes called the Lower Flammable Limit.

Question 12

Percentage vs ppm

Answer 12

1% = 10,000 ppm

Question 13

What is the UEL? (context fire risk)

Answer 13

UEL = Upper Explosive Limit

The concentration (%) above which a gas will not burn.

Question 14

What is the flammable range? Specifically for H2S.

Answer 14

The flammable range, is the range between the LEL and the UEL.
H2S has a range of 4 - 44.

(4% to 44%)

Question 15

What H2S-specific sections are in the BC OHS Regulation?

Answer 15

The only H2S-specific regulations are under part 23, Oil and Gas.

Question 16

What H2S-specific sections are in the BC OHS Regulation?

Answer 16

The only H2S-specific regulations are under part 23, Oil and Gas.

Question 17

Why do most OHS regulations in Canada not have specific H2S sections in industries where H2S is a known hazard?

Answer 17

While there are not specific H2S sections/requirements, the general requirements for chemical hazards and confined space hazards provide sufficient regulation that would include H2S hazards.

Question 18

List 5 areas of regulation (OHS & public safety) that apply to H2S, anhydrous ammonia, and chlorine gas.

Answer 18

• Design standards for equipment used in processes.
• Design standards for process facilities.
• Mandatory or highly recommended qualifications for workers who operate processes.
• Requirement for safe work procedures for normal work and emergency response.
• Exposure control plans.

Question 19

Why might management of a H2S OHS program be potentially more challenging than for ammonia or chlorine?

Answer 19

There are uncertainties about the presence and quantity of H2S in a given situation.

Emergency scenario’s involving release and exposure of H2S can be sudden and with severe consequences.

Question 20

How should an OHS program for H2S be started/approached?

Answer 20

1, Read the regulations and the ‘nearly law’ best practices carefully/completely.

2, Read the guidance documents from OHS and energy board regulators carefully/completely.

Question 21

What is the maximum recommended short term exposures to H2S in a given day per the ACGIH?

Answer 21

5.

The ACGIH recommends no more than 5 short term exposures to H2S in a day.
American Conference of Governmental Industrial Hygienists.

Question 22

How many breaths of high H2S concentrations are necessary to kill a worker?

Answer 22

1.

Question 23

Name three broad areas of regulation for H2S.

Answer 23

1, General OHS regulations for hazardous materials.

2, Specific OHS regulations for activities where H2S is a known hazard.

3, Public safety laws, such as those administered by energy boards.

Question 24

Why would a worker remain in an area of high H2S concentrations when there is a distinct/nauseating odor?

Answer 24

At high levels, H2S dissolves into the blood and paralyses the olfactory part of the brain, eliminating the sense of smell. Workers may be unaware of the high levels.

Question 25

What is upstream or downstream oil and gas production?

Answer 25

The oil and gas production supply chain is divided into three areas: upstream, midstream, downstream.

Upstream - identification, extraction, and production of raw materials

Downstream - Post production of crude oil and natural gas

Midstream - Connects up/down stream. Transportation & storage.

Question 26

What is H2S Alive?

Answer 26

A 1 day course offered by ENFORM for people entering the oil/gas industry. Covers H2S safety.

It is nearly impossible to work in upstream oil and gas without this course.

Question 27

List three energy regulators that indirectly improve the safety of oil & gas workers.

Answer 27

The Canada Energy Regulator

Alberta Energy Regulator

BC Oil and Gas Commission

All three enforce laws to protect the public, which also result in worker protection.