Washington Administrative Code
Title 173 - Ecology, Department of (See also Titles 197, 317, 372, and 508)
Chapter 173-490 - Emission standards and controls for sources emitting volatile organic compounds (VOC)
Section 173-490-201 - Petroleum liquid storage in external floating roof tanks
Universal Citation: WA Admin Code 173-490-201
Current through Register Vol. 24-06, March 15, 2024
(1) Specific applicability.
(a) This section shall apply to all petroleum
liquid storage vessels equipped with external floating roofs, having capacities
greater than 150,000 liters (40,000 gallons), and as qualified in WAC
173-490-025.
(b) This section does not apply to petroleum
liquid storage vessels that:
(i) Are used to
store waxy, heavy pour crude oil; or
(ii) Have capacities less than 1,600,000
liters (420,000 gallons) and are used to store produced crude oil and
condensate prior to lease custody transfer; or
(iii) Contain a petroleum liquid with a true
vapor pressure of less than 10.5 kPa (1.5 psia); or
(iv) Contain a petroleum liquid with a true
vapor pressure less than 27.6 kPa (4.0 psia); are of welded construction; and
presently possess a metallic-type shoe seal, a liquid-mounted foam seal, a
liquid-mounted liquid filled type seal, or other closure device of demonstrated
equivalence approved by ecology; or
(v) Are of welded construction, equipped with
a metallic-type shoe primary seal and have secondary seal from the top of the
shoe seal to the tank wall (shoe-mounted secondary seal).
(2) Provisions for specific processes.
(a) No owner(s) or operator(s) of a
petroleum liquid storage vessel shall store a petroleum liquid in that vessel
unless:
(i) The vessel has been fitted with:
(A) A continuous secondary seal extending
from the floating roof to the tank wall (rim-mounted secondary seal);
or
(B) A closure or other device
which controls VOC emissions with an effectiveness equal to or greater than a
seal required under WAC
173-490-201(2)(a)(i)(A)
and approved by ecology.
(ii) All seal closure devices meet the
following requirements:
(A) There are no
visible holes, tears, or other openings in the seal or seal fabric;
(B) The seal is intact and uniformly in place
around the circumference of the floating roof between the floating roof and the
tank wall; and
(C) For vapor
mounted primary seals, the accumulated area of gaps exceeding 0.32 cm (1/8
inch) in width between the secondary seal and the tank wall shall not exceed
21.2 cm2 per meter of tank diameter (1.0
in.2 per foot of tank diameter), as determined by
the method in WAC
173-490-201(3).
(iii) All openings in the external
floating roof, except for automatic bleeder vents, rim space vents, and leg
sleeves, are:
(A) Equipped with covers, seals,
or lids in the closed position except when the openings are in actual use;
and
(B) Equipped with projections
into the tank which remain below the liquid surface at all times.
(iv) Automatic bleeder vents are
closed at all times except when the roof is floated off or landed on the roof
leg supports;
(v) Rim vents are set
to open when the roof is being floated off the leg supports or at the
manufacturer's recommended setting; and
(vi) Emergency roof drains are provided with
slotted membrane fabric covers or equivalent covers which cover at least ninety
percent of the area of the opening.
(b) The owner(s) or operator(s) of a
petroleum liquid storage vessel with an external floating roof subject to this
chapter shall:
(i) Perform routine inspections
annually in order to insure compliance with WAC
173-490-201(2)(a)
and the inspection shall include a visual inspection of the secondary seal
gap;
(ii) Measure the secondary
seal gap annually in accordance with WAC
173-490-201(3)
when the floating roof is equipped with a vapor-mounted primary seal;
and
(iii) Maintain records of the
types of volatile petroleum liquids stored, the maximum true vapor pressure of
the liquid as stored, and the results of the inspections performed in WAC
173-490-201(2)(b)(i) and
(ii).
(c) The owner(s) or operator(s) of a
petroleum liquid storage vessel with an external floating roof exempted from
this chapter by WAC
173-490-201(1)(b)(iii),
but containing a petroleum liquid with a true vapor pressure greater than 7.0
kPa (1.0 psi), shall maintain records of the average monthly storage
temperature, the type of liquid, and the maximum true vapor pressure for all
petroleum liquids with a true vapor pressure greater than 7.0 kPa.
(d) Copies of all records under WAC
173-490-201(2)(b) and
(c) shall be retained by the owner(s) or
operator(s) for a minimum of two years after the date on which the record was
made.
(e) Copies of all records
required under WAC
173-490-201 shall immediately be
made available to the director, upon verbal or written request, at any
reasonable time.
(3) Testing and monitoring.
(a) The owner or
operator of a storage vessel covered under WAC
173-490-201 shall demonstrate
compliance by the methods of this subsection or an alternative method approved
by ecology.
(b) A person proposing
to measure the seal fit of a storage vessel in order to comply with this
section shall notify ecology of the intent to measure not less than five
working days before the measurement so the director or a representative may
observe the measurement if desired.
(c) Compliance with WAC
173-490-201(2)(a)(ii)(C)
shall be determined by physically measuring the length and width of all gaps
around the circumference of the secondary seal in each place where a 0.32 cm
(1/8 in.) diameter probe passes freely (without forcing or binding against the
seal) between the seal and the tank wall and summing the area of the individual
gaps.
Statutory Authority: Chapter 70.94 RCW. 91-05-064 (Order 90-06), § 173-490-201, filed 2/19/91, effective 3/22/91. Statutory Authority: RCW 70.94.331 and 70.94.395. 80-11-062 (Order DE 80-18), § 173-490-201, filed 8/20/80.
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