Ammonia storage tank

[tarafdar]

What are the points to be considered for selecting between single wall & double wall tanks for ammonia storage?Tanks capacity 5000-20000MT.Is there any code & standard for this?Is dyke or bund- wall mandatory for ammonia storage tanks?

[Antonio]

Tarafdar

I didnt upload the material because I dont know how, so
Look for:
1 - EMFA booklet Ammonia - production and storage
2 - Ammonia, Principles and Industrial Practice
3 - Canadian fertililizer industry storage and handling guideline


WAC 296-24-51013 Refrigerated storage.

This section applies specifically to systems utilizing tanks for the storage of anhydrous ammonia under refrigerated conditions. All basic rules of WAC 296-24-51009 apply to this section unless inconsistent with the requirements of this section.

(1) Design of tanks.

(a) Tanks may be designed for any storage pressure desired as determined by economical design of the refrigerated system.

(b) The design temperature shall be the minimum temperature to which the container will be refrigerated and shall be so designated.

(c) Containers with a design pressure exceeding 15 p.s.i.g. shall be constructed in accordance with WAC 296-24-51009(2) and the material shall be selected from those listed in API Standards 620, 4th edition 1970, Recommended Rules for Design and Construction of Large, Welded Low-Pressure Storage Tanks, Tables 2.02, R.2.1, R.2.2, R.2.3 or R.2.4.

(d) Tanks with a design pressure of 15 p.s.i.g. and less shall be constructed in accordance with the general requirements of API Standard 620, 4th edition, 1970, including Appendix R.

(e) When austenitic steels or nonferrous materials are used, the ASME Code shall be used as a guide in selection of materials for use at the design temperature.

(f) The filling density for refrigerated storage containers shall be such that the container will not be liquid full at a liquid temperature corresponding to the vapor pressure at the start-to-discharge pressure setting of the safety-relief valve. (New 1-22-76)

(2) Installation of storage tanks.

(a) Tanks shall be supported on suitable noncombustible foundations designed to accommodate the type of tank being used.

(b) Adequate protection against flotation or other water damage shall be provided wherever high flood water might occur.

(c) Tanks for product storage at less than 32°F shall be supported in such a way, or heat shall be supplied, to prevent the effects of freezing and consequent frost heaving.

(d) The area surrounding a refrigerated tank or group of tanks shall be provided with drainage, or shall be diked to prevent accidental discharge of liquid from spreading to uncontrolled areas.

(e) When drainage is employed, a slope of not less than one percent shall be provided. The drainage system shall terminate in an impounding basin having a capacity as large as the largest tank served.

(f) Provision shall be made for drainage of rain water from the diked or impounding area. Such drainage shall not permit the release of ammonia.

(g) When a dike surrounding the tank is employed, the capacity of the diked enclosure shall be as large as the largest tank served.

(h) The walls of a diked enclosure or the wall of an impounding basin used in a drainage system shall be of earth, steel or concrete designed to be liquid tight and to withstand the hydrostatic pressure and the temperature. Earth walls shall have a flat top at least 2 feet wide. The slope shall be stable and consistent with the angle of repose of the earth used.

(i) The ground in an impounding basin or within a diked enclosure, should be graded so that small spills, or the early part of a large spill, will accumulate at one side or corner contacting a relatively small area of ground and exposing a relatively small surface area for heat gain. Shallow channels in the ground surface or low curbs of earth can help guide the liquid to these low areas without contacting a large ground area.

[Arrayxxx]

I'm currently on project build an ammonia tank with capacity 20000mt
my design for that tank is two tank in one, single containment, inner tank with open top design annular flat bottom and outer tank with supported dome roof and suspended deck.

i'm not yet know reference point for decide using single wall or double wall..
I'm only refer to api620 app r

[abdullah122511]

Use EFMA guidelines-2008, BS 7777 for reference. Double wall full containment is always preferable for high degree of safety and reliability. However, any company decide differently due to local regulations, costs involved, and personal choice.

[abdullah122511]

Kindly if anyone has CGA G 2.1 2014. We are working for installing a second 5000MT ammonia storage tank therefore need to consult this code.

[dynamicvibration]

Can you share more detail on like design & drawings if possible.
It will be great help.