Mineral fertilizer warehouse - arch calculation

6. Guidelines for protection of building structures.

Protection against chemically aggressive effects of mineral fertilizers.

During operation, aggressive media cause a decrease in wood strength by 1525%. Therefore, when designing structures, structural and chemical protection measures are provided.

Protective treatment with coatings against humidification and aggressive environment is required. The latter is performed either by surface application of paint materials (perchlorovinyl enamel KV785 and varnish KV784) or by impregnation with synthetic resins (epoxy resins ZP755, EP-773). Ends of wooden elements are treated with said solutions 6-8 times .

Bioprotection of structures.

Since mineral fertilizer salts are antiseptics, bioprotective treatment of wood is not done.

Fire protection.

Unprotected wood belongs to the group of burned materials. Fire safety of wooden structures is characterized by fire resistance limit and fire propagation limit.

For preliminary assessment of fireproof wood treatment efficiency in laboratory conditions it is allowed to test fireproof wood according to GOST 1636376 "Wood. Determination of fire-retardant properties of coatings and impregnating compositions by ceramic pipe method. "

In accordance with Note 2 to Table 3 of SNiP II280, wooden slabs, floorings and slabs of the buildings and structures listed in Item 1.7 (2.7), as well as elements of hinged panels of external walls and internal bearing walls (partitions) of these buildings and structures shall be subjected to deep impregnation with flame retardants.

Fire-retardant treatment does not reduce the rate of charring of wood and does not increase the fire resistance limit of wooden structures with a cross section of more than 120 x 120 mm, for other structures the fire resistance limit can be increased by 5 minutes. The use of fire-retardant treatment can reduce the fire propagation limits on wooden structures or transfer wood to a group of difficult-to-burn materials.

Quality of fire-retardant treatment shall ensure reduction of fire propagation limit on wooden structures up to 40 cm for vertical elements, up to 25 cm for horizontal ones or results of tests of protected wood according to CT CMEA 243780 shall meet requirements for hard-burning materials.

Inflatable coatings are applied to the surface of wooden structures by pneumatic spraying. Impregnating compositions are applied to

wood surface or wood is impregnated by deep impregnation method.

For surface fire protection, it is recommended to use: wood coating fire-retardant phosphate OFP9 (GOST 2379080), wood coating intumescent fire-retardant HPA (GOST 1313082), TKEF composition - a solution of trichloroethyl phosphate in four - carbon chloride. For deep impregnation of wood, the composition of MS 1:1 is recommended - an aqueous solution of a mixture of diammonium phosphate, ammonium sulfate and sodium fluoride.

The expandable coatings form a foamy carbon layer in the process of exposure to high temperatures, which is a coked melt foamed with the help of gaseous products released during heating. The resulting layer creates a heat insulating shield and increases the heating time of the wood to the decomposition temperature.

Fire-retardant effect of flame retardants is achieved due to the fact that heat is absorbed during their thermal decomposition, their decomposition products create a protective shell of inert gases near the surface of wood and bind active radicals of decomposition products.

For the protection of bearing wooden structures made of solid wood, intumescent fire-retardant compositions, impregnating compositions, as well as compositions applied to the surface are recommended. For glued wooden structures, it is recommended to use swollen compositions and flame retardants applied to the surface of the structures.

It is recommended to use flame retardants for deep impregnation of wood under pressure and applied to the surface for fire protection of elements of wooden frames of enclosing structures.

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