NEBOSH IOG Exam : Element 1 questions with verified
answers
(a) Identify properties of hydrogen. (4)
(b) Outline hazards associated with hydrogen. (4) Ans✓✓✓-a. Hydrogen is lighter
than air (less than 1 vapour density)
It is highly flammable and explosive
It is colourless and odourless.
It can react vigorously with oxidising agents
b. The main hazard with hydrogen is its risk of explosion and fire due to it being
easily ignitable when presented with even a low energy ignition source (even at
very low air/Hydrogen concentrations). It can be an asphyxiant at higher
concentrations. It is stored under pressure and when containers/cylinders are
punctured (for example), a rapid explosive release of gas is likely.
(a) Outline conditions that are necessary to ignite a flammable liquid. (4)
(b) Outline control measures that could help reduce the risk of fire from a storage
tank containing flammable liquid. (4) Ans✓✓✓-a. The temperature falls within
the range between 21C and 55C whereby sufficient vapours will be produced to
create an air/vapor mix within the explosive range (between LFL and UFL). In
order for the above to happen, there must be sufficient air and sufficient fuel (to
create the vapours) too. There must also be an ignition source available (one
essential component of the fire triangle).
b. Passive control measures are used to reduce the risk of fire from a storage
tank. Passive measure could include ensuring that any and all ignition sources
(smoking, hot works etc) are kept clear or are mitigated using intrinsically safe
control devices. To reduce the risk of static buildup & discharge, tanks should be
designed to avoid splashing while filling (i.e. use bottom filling). Proper electrical
grounding at filling areas where hoses are to be attached to tanker trucks must be
, installed. The tank would be outfitted with gas detectors strategically placed in
areas where leaking vapor is most likely to accumulate (check vapour density
values). Fire eyes and heat detectors would also be installed. On the human side,
the area must be made secure to ensure that access by unauthorized people is
not possible. Those entering the area must be qualified and/or been through
induction training.
1.) In your safety role on an offshore oil production platform, you have been
asked to take part in a risk assessment and subsequent procedures for the
preparation and repair of a large, electrically-driven pump containing a hot,
flammable liquid. The pump needs to be stopped, the large suction and discharge
valves closed, the pump contents removed and the pump inerted before the
repair is carried out.
a) Identify hazards AND, in EACH case, outline an associated risk with the
preparation of the pump. (8)
b) Outline control measures that should be taken for the repair of the pump. (8)
c) Identify locations where locks and associated tags should be applied for Lock
Out, Tag Out (LOTO). (2)
d) Identify types of worker who may attach personal locks within LOTO in this
situation. (2) Ans✓✓✓-1a Electrical shock
2a Heat Explosion/Fire
3a Gravity
4a Motion
5a Asphyxiation
6a Pressure
7a Environmental/Spill
8a Shift Changeover/Miscommunications
answers
(a) Identify properties of hydrogen. (4)
(b) Outline hazards associated with hydrogen. (4) Ans✓✓✓-a. Hydrogen is lighter
than air (less than 1 vapour density)
It is highly flammable and explosive
It is colourless and odourless.
It can react vigorously with oxidising agents
b. The main hazard with hydrogen is its risk of explosion and fire due to it being
easily ignitable when presented with even a low energy ignition source (even at
very low air/Hydrogen concentrations). It can be an asphyxiant at higher
concentrations. It is stored under pressure and when containers/cylinders are
punctured (for example), a rapid explosive release of gas is likely.
(a) Outline conditions that are necessary to ignite a flammable liquid. (4)
(b) Outline control measures that could help reduce the risk of fire from a storage
tank containing flammable liquid. (4) Ans✓✓✓-a. The temperature falls within
the range between 21C and 55C whereby sufficient vapours will be produced to
create an air/vapor mix within the explosive range (between LFL and UFL). In
order for the above to happen, there must be sufficient air and sufficient fuel (to
create the vapours) too. There must also be an ignition source available (one
essential component of the fire triangle).
b. Passive control measures are used to reduce the risk of fire from a storage
tank. Passive measure could include ensuring that any and all ignition sources
(smoking, hot works etc) are kept clear or are mitigated using intrinsically safe
control devices. To reduce the risk of static buildup & discharge, tanks should be
designed to avoid splashing while filling (i.e. use bottom filling). Proper electrical
grounding at filling areas where hoses are to be attached to tanker trucks must be
, installed. The tank would be outfitted with gas detectors strategically placed in
areas where leaking vapor is most likely to accumulate (check vapour density
values). Fire eyes and heat detectors would also be installed. On the human side,
the area must be made secure to ensure that access by unauthorized people is
not possible. Those entering the area must be qualified and/or been through
induction training.
1.) In your safety role on an offshore oil production platform, you have been
asked to take part in a risk assessment and subsequent procedures for the
preparation and repair of a large, electrically-driven pump containing a hot,
flammable liquid. The pump needs to be stopped, the large suction and discharge
valves closed, the pump contents removed and the pump inerted before the
repair is carried out.
a) Identify hazards AND, in EACH case, outline an associated risk with the
preparation of the pump. (8)
b) Outline control measures that should be taken for the repair of the pump. (8)
c) Identify locations where locks and associated tags should be applied for Lock
Out, Tag Out (LOTO). (2)
d) Identify types of worker who may attach personal locks within LOTO in this
situation. (2) Ans✓✓✓-1a Electrical shock
2a Heat Explosion/Fire
3a Gravity
4a Motion
5a Asphyxiation
6a Pressure
7a Environmental/Spill
8a Shift Changeover/Miscommunications
