Storage tanks are highly critical components of an LNG plant. LNG tanks can be categorized from different aspects:
§ Fix or on carrier tanks
§ Containment type
§ Above ground, in-ground types & underground
Fixed storage tanks are normally made with 4 main containment types:
• Single containment: This tank has an inner tank made of 9 % nickel and an outer tank made carbon steel. In case of leakage there is no protection other than having a large construction free area. For this reason this type of tank is not used for a long time.
• Double containment: This type has a secondary containment steel or concrete dike wall close to the vapor containing the outer tank.
• Full containment: This type has a 9 % inner tank and a concrete outer tank which allows leakage to exit only from the roof. This is the most constructed LNG tank type and requires much less land.
• Membrane type: This type – which is mainly an in-ground or underground type – uses a membrane cladding of stainless steel on the insulation and a concrete outer tank. The construction cost of this type is high – as such this design is applied when very limited land is available.
Various design codes govern the construction of LNG tanks. Considerin very low operating temperature 9 % nickel is the main grade used for fabrication tanks.
• ASME BPVC Sec. VIII, Div. 1
• ASME BPVC Sec. VIII Div. 2 Alternative rules
• API Standard 620:
• BS EN 14620-1:
• JIS B8265:
• JIS B8267
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