روز پنجشنبه ای دیگر و دلتنگی

FLOATING ROOF TANK

A Floating Roof as its name implies, actually floats on the surface of the liquid in the tank. As the liquid level changes the roof is designed to move up and down with the liquid level - i.e. Filling, Emptying, Expansion and Contraction due to temperature changes. This type of tank roof minimizes the vapor space between it and the liquid surface. Since there is no large vapor space for the liquid to evaporate into, vapor losses are also minimized
In its simplest form, the floating roof is merely a large, disc, slightly smaller in diameter than the tank shell. It is fitted with a system of flexible 'shoes' to close the space between the edge of the roof and the tank shell in order to minimize vapor loss

In modern usage, there are two main designs of floating roof
The 'Pontoon' roof
The 'Double-Deck' roof

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ASTM A193

This specification covers alloy steel and stainless steel bolting material for pressure vessels, valves, flanges, and fittings for high temperature or high pressure service, or other special purpose applications. Ferritic steels shall be properly heat treated as best suits the high temperature characteristics of each grade. Immediately after rolling or forging, the bolting material shall be allowed to cool to a temperature below the cooling transformation range. The chemical composition requirements for each alloy are presented in details. The steel shall not contain an unspecified element for ordered grade to the extent that the steel conforms to the requirements of another grade for which that element is a specified element. The tensile property and hardness property requirements are discussed, the tensile property requirement is highlighted by a full size fasteners, wedge tensile testing

ASTM A194

This specification covers a variety of carbon, alloy, and martensitic and austenitic stainless steel nuts. These nuts are intended for high-pressure or high-temperature service, or both. Bars from which the nuts are made shall be hot-wrought. The material may be further processed by centerless grinding or by cold drawing. Austenitic stainless steel may be solution annealed or annealed and strain-hardened. Each alloy shall conform to the chemical composition requirements prescribed. Hardness tests, proof of load tests, and cone proof load tests shall be made to all nuts to meet the requirements specified