8 replies to this topic

[alokjaiswal]

Dear all,

I request all the members to enumerate the Safety requirement while designing an Atmospheric Ammonia Storage Tank of Double walled integrity. Also, provide some literature on safety as well as design requirements of Ammonia Storage tank.

Alok Jaiswal.

[wojtar]

Read this short article. Puts some light on safety dealing with atmospheric ammonia storage:

http://www.uhdeindia...oniastorage.pdf

[kkala]

Thanks to wojtar for the ammonia storage reference, very useful indeed.
Having worked in a fertilizer plant (1975-81), liquid ammonia was pipe transferred from nearby producer and stored in two single wall pressure bullets for consumption. In 1986 an ammonia storage (located in a concrete cylinder higher than it) was made at nearby port, which had not been officially approved by authorities until the shutdown of the plant in 2007. Another fertilizer plant, located in populated Athens area (Greece), shut down in 1992; its ammonia storage is said to have contributed to it. Even though refrigerated ammonia storage will minimize (percentagewise) ammonia vapors released during an accident, every care should be taken, not only to assure state approval of the installation but also to prevent future potential problems.
The former concerns Hazop study, Safety (Seveso-II) study (with quantitative risk assessment) submitted to authorities, fire fighting study submitted to authorities, and all rest necessary documents for permit. These may differ somehow from country to country. Emergency plant to minimize any accident consequences (prepared here even for non credible catastrophic scenaria) has to be prepared. All these may be considered as formal obligations, but they also promote safety and alert.
The latter concerns measures not mandatory by present state requirements, but likely to prevent problems in future. These greatly depend on the local area. For instance, over here an industrial installation is usually built in an isolated place, so none is disturbed. As the time passes, cities are expanded and communities are built nearby, disturbed by the installation. An ammonia storage make the industrial installation more risky in this case. Perspectives of such issue would be minimized, if ammonia installation is built in a recognized big industrial area. If this is not possible, a big land area around the installation had better be purchased by ammonia storage owner for safety.
So location of ammonia storage is a factor to be considered, as well as prevailing wind, which should not be to densely populated areas. Several other issues had better be considered in advance, considering legal, environmental and social matters.

[wojtar]

Thanks to wojtar for the ammonia storage reference, very useful indeed.
Having worked in a fertilizer plant (1975-81), liquid ammonia was pipe transferred from nearby producer and stored in two single wall pressure bullets for consumption. In 1986 an ammonia storage (located in a concrete cylinder higher than it) was made at nearby port, which had not been officially approved by authorities until the shutdown of the plant in 2007. Another fertilizer plant, located in populated Athens area (Greece), shut down in 1992; its ammonia storage is said to have contributed to it. Even though refrigerated ammonia storage will minimize (percentagewise) ammonia vapors released during an accident, every care should be taken, not only to assure state approval of the installation but also to prevent future potential problems.

Thanks fot your post. I would like to know your opinion about such case:
There will be large ammonia storage tank located in some big fertilizers plant. The tank is so called "full containment" (tank with double wall). Both inner and outer tank are designed to handle refrigerated ammonia (-32degC), liquid and vapour. Additionally there will be another wall around the tank made from reinforced concrete.

Does it make sense to build another protection like earth dyke around full containment tank (protected with concrete wall) or to support concrete walls with external earthen embankment? Is it something unusual.

Everybody probably know about that famous ammonia tank colapse in Jonava.

[kkala]

There will be large ammonia storage tank located in some big fertilizers plant. The tank is so called "full containment" (tank with double wall). Both inner and outer tank are designed to handle refrigerated ammonia (-32degC), liquid and vapour. Additionally there will be another wall around the tank made from reinforced concrete.
Does it make sense to build another protection like earth dyke around full containment tank (protected with concrete wall) or to support concrete walls with external earthen embankment? Is it something unusual.
Everybody probably knows about that famous ammonia tank colapse in Jonava.

I have found information on the 7000 ton liquid ammonia tank accident near Jonava, good site for this is http://books.google....ccident&f=false. That tank was "splitted" quite near its base and smashed onto the concrete bund wall, which explains the spirit of your question.
Mentioned site recommends: (α) Effective control to avoid unexpected feed of warm liquid NH3 into the refrigerated tank (which caused the accident). (β) PRVs to cover all upset conditions (γ) weaker shell-to-roof (or roof) area, to avoid loss of liquid containment at critical conditions (δ)peripheral concrete wall to contain all stored liquid (only). Best available technique (BAT) for liquid NH3 storage (http://www.diquima.u...cs/amonia00.pdf) mentions some of above requirements (as well as other), but nothing about external wall.
Consequently ammonia tank of previous post would be adequately safe under present knowledge, if above measures have been applied, as well as material & welding inspections and rest code requirements. Is there any specific condition requiring additional measures, like additional earth dike or earth to externally support the concrete wall? At first look, the answer is no; causes of previous accident are practically eliminated through the above recommendations. But second thought can recommend additional measures to be investigated, e.g. as follows.
1. Has the area frequent earthquakes? An unexpectedly strong one could rupture the tank (even pour liquid out from tank top). Moving liquid could splash over the concrete walls and stop at dikes. Civil could assess.
2. What about an unusually strong lightning? Can it cause same conditions as previous?
3. There may be other conditions of tank rupture, e.g. sabotage.
Similar cases are usually thought in the process of time and are assessed during the hazop study or safety study. I think for ammonia tanks a safer than single contingency principle has to be applied.

Edited by kkala, 09 July 2011 - 12:27 PM.

[kkala]

Just a note, concerning previous post about ammonia storage safety and risk from physical events, like earthquake, lightning, etc. State regulations suggest several values for safe design. But, at least here, these concern mainly buildings; there are decrees for industrial installations, but a big ammonia storage tank needs even stricter safety design criteria. A failure of usual industrial installation may have victims, but a rupture of a big ammonia tank may have much more. Ok, if there are decrees for ammonia storage; even so peculiarities of the specific installation should be considered. Otherwise one should start from the basics and create the necessary safety environment.
I have seen this principle applied for an alumina Project to be located on an area prone to earthquakes. A critical element of alumina factor is its precipitators, agitated tanks of dia 14 m and height 29.3 m. A specific static study was conducted, installation was on rock, and tanks were covered, to avoid splashing of liquid out of them due to oscillations in a strong earthquake. I do not know other covered precipitators, they are uncovered in a similar plant ~ 150 km off, but the study recommendations were respected.

Editing note, Dec 10th 2011: Corrected precipitator dimensions, dia=14 m, height = 29.3 m

Edited by kkala, 10 December 2011 - 03:45 PM.

[wojtar]

Just a note, concerning previous post about ammonia storage safety and risk from physical events, like earthquake, lightning, etc. State regulations suggest several values for safe design. But, at least here, these concern mainly buildings; there are decrees for industrial installations, but a big ammonia storage tank needs even stricter safety design criteria. A failure of usual industrial installation may have victims, but a rupture of a big ammonia tank may have much more. Ok, if there are decrees for ammonia storage; even so peculiarities of the specific installation should be considered. Otherwise one should start from the basics and create the necessary safety environment.
I have seen this principle applied for an alumina Project to be located on an area prone to earthquakes. A critical element of alumina factor is its precipitators, agitated tanks of dia~4.5 m and height~40 m. A specific static study was conducted, installation was on rock, and tanks were covered, to avoid splashing of liquid out of them due to oscillations in a strong earthquake. I do not know other covered precipitators, they are uncovered in a similar plant ~ 150 km off, but the study recommendations were respected.

Thanks again.
In our case no earthquake is expected, lightning -> as usual during summer, terrorist attacs -> probably not but who knows.
Regards

[kkala]

So usual industrial installations will be so designed as to be (theoretically) safe against the strongest earthquake or lightning to occur (say) once every 200 years. This comes from statistics and theory, and in fact considers higher intensities as non credible. However this specified probability should be also dependent on the catastrophic extent expected from the considered failure. So a big ammonia storage should be (theoretically) safe from the strongest calamity to occur (say) every 1000 years. It had better be designed and constructed to stricter safety standards. These are not specified by Process Engineer, yet the latter can inform civil or mechanical engineers about the risks in detail, to apply proper standards. Local historical data is also scrutinized, and probably stricter design parameters are deducted from them (from the basics). Reevaluation of available site data by civil / mechanical engineers, after being aware of ammonia risks, is good for a safe installation.
I followed this in a local alumina project. My understanding was that it is difficult to assess all probable risks to the right degree. Some may be overestimated, but (worse) some may be underestimated or neglected. That is why safety study and Hazop study should be real, not limited to formalities. And even so it is not easy to "catch and frame" all possible risks.

Edited by kkala, 18 July 2011 - 06:44 AM.

[tarafdar]

Dear Mr. Jaiswal,
You may take help from the following code and standards:
1.API 620 10th edition for design
2.API 650 for design
3.API 520 Appendix D for insulation and relief valve design
4.DIN 4119 Part-1 for design Part-2 for calculations
5.ANSI K61.1-1999 for safety requirements
6.Compressed Gas Association(CGA)
CGA-G2.1 for safety requrements
7.ASME Section-viii Div-i/ii for design
8.ASME B31.3 for process piping
B31.5 for refrigeration piping
9.ASTM A516 Gr.70 for material
10.BS 7777-2:1993 for design
11.UL 142 for design
12.OSHA 1910.111(a)(1)(i) for design
13.National Fire Protection Association NFPA
NFPA 30 for safety