Petroleum Peculiarities. Fuels are lighter than water, and when mixed with water, the fuel will float on
top of the water.
Petroleum fuels breathe. They expand as temperatures increase and contract as temperatures
decrease. As the fuel expands due to high temperatures, light ends are lost. When heated fuel begins to
cool and contract, water accumulates in the fuel through condensation.
PART D. CONFINED SPACE ENTRY
As a petroleum staff NCO a major and ongoing responsibility involves the vapor freeing and cleaning of
petroleum storage tanks, railcars, and tank trucks. Safety is of the utmost importance when performing any
operation dealing with petroleum and the various methods of storage. The following information concerns your
general responsibilities and the training of personnel having to do with the federal regulations that govern tank
Sources of hazards. Storage tanks, tank cars, and tank trucks which have been in service, may contain
residues of dangerous materials, whether left over from the transportation of hazardous cargoes.
Forced air ventilation. Forced air ventilation shall be sufficient to keep the atmospheric concentration of
flammable materials below 10% of the lower flammable limit (LFL) (or lower explosive limit (LEL), whichever
term is used locally). Appropriate respirators will be provided and shall be used in addition to providing forced
ventilation if the forced ventilation does not maintain acceptable respiratory conditions.
Attendant. The area supervisor shall designate an employee to maintain communication by employer specified
means with employees working in tanks to ensure their safety. The attendant may not enter any permit entry
confined space to rescue an entrant or for any other reason, unless authorized by the rescue procedure and,
even then, only after calling the rescue team and being relieved by an attendant or another worker.
Communications and observation. Communications between attendant and entrant(s) shall
throughout entry. Methods of communication that may be specified by the permit include voice, voice powered
radio, tapping or rapping codes on tank walls, signaling tugs on a rope, and the attendant's observation that work
activities such as chipping, grinding, welding, spraying, etc., which require deliberate operator control continue
normally. These activities often generate so much noise that the necessary hearing protection makes
communication by voice difficult.
Rescue procedures. Acceptable rescue procedures include entry by a team of employee-rescuers, use of public
emergency services, and procedures for breaching the tank. The area permit specifies which procedures are
available, but the area supervisor makes the final decision based on circumstances. (Certain injuries may make
it necessary to breach the tank to remove a person rather than risk additional injury by removal through an
existing manhole. However, the supervisor must ensure that no breaching procedure used for rescue would
violate terms of the entry permit. For instance, if the tank must be breached by cutting with a torch, the tank
surfaces to be cut must be free of volatile or combustible coatings within 4 inches (10.16 cm) of the cutting line
and the atmosphere within the tank must be below the LFL.
Retrieval line and harnesses. The retrieval lines and harnesses generally required under this standard are
usually impractical for use in tanks because the internal configuration of the tanks and their interior baffles and
other structures would prevent rescuers from hauling out injured entrants. However, unless the rescue procedure
calls for breaching the tank for rescue, the rescue team shall be trained in the use of retrieval lines and
harnesses for removing injured employees through manholes.
Control of atmospheric hazards. A "used" tank shall be brought into areas where tank entry is authorized only
after the tank has been emptied, cleansed (without employee entry) of any residues, and purged of any potential
Permits. An entry permit valid for up to 1 year shall be issued prior to authorization of entry into used tank
trailers, dry bulk trailers or trucks. In addition to the pre-entry cleaning requirement, this permit shall require the
employee safeguards specified for new tank fabrication or construction permit areas.
Authorization. Only the area supervisor may authorize an employee to enter a tank trailer, dry bulk trailer or
truck within the permit area. The area supervisor must determine that the entry permit requirements have been
met before authorizing entry.