Mica Shield

Product Item：OV-002

Material: Mica sheet

Usage: Protect Gauge Glass,observe liquid level

Size: various

Working temperature: up to 600 deg. C

Description

MICA SHIELDS provide the best protection possible, to flat transparent; sight glasses in water and liquid level gauges and columns in high pressure steam boilers. The SHIELDS retain basic strength and increase the service life of sight glasses when used at increased steam pressures and high working temperatures. MICA SHIELDS also provide perfect visibility for monitoring the nature or degree of combustion in blast furnaces of steam boilers. Natural mica has extremely high heat resistance; transparency; optical clarity; flexibility; flatness and is unbreakable. The transparency of mica is not affected by the repeated fluctuations in heating and cooling and is not attacked by most of the gases and vapors it might come into contact with. In addition, mica resists shocks, strains and vibrations and therefore can easily be used in place of glass where there is a likelihood of exposure to radiant heat, breakage or cracking. As steam boilers are frequently shut-down and started up again, this places extreme demands on the transparent glasses fitted between CAF sealing gaskets and cushion joints of the level gauges. It is therefore essential to protect these glasses with MICA SHIELDS by fitting them on the side facing the medium chamber.

MICA SHIELDS are a must where saturated steam pressure exceeds 350 psi (up to 5689 psi) and working temperatures exceed 196 deg. C (up to 600 deg. C). MICA SHIELDS also protect the inner surfaces of the transparent glasses against erosion from chemical abrasion and from corrosive chemical effects of alkaline solutions, boiler waters, caustics, hydrofluoric acids, hot concentrated phosphoric acids, sodium and potassium hydroxides and other contaminated viscous or corrosive media. It provides an excellent sealing strength against acids, sodium, water, air and oil at extreme pressures and temperatures and completely eliminates the risk of cracks, breakage, jerks, shocks, combustion effects, etc. In fact, MICA SHIELDS serve effectively in closing the spy holes of observation doors of level gauges and columns.

Size and Dimentions

Grade of Mica Shield

Suitable for saturated steam service from 600 to 1500 PSIG
Conforms to ASTM D351 specifications

Grade	Outward appearance	Description
V-1	Clear	Hard, of uniform color, nearly flat, free of all stains, foreign inclusion, cracks, and other similar defects.
V-2	Clear and Slightly Stained	Hard, of uniform color, nearly flat and may contain slight crystallographic discoloration, and very slight air inclusions and not more than one fourth of the usable area.
V-3	Fair Stained	Hard, of uniform color, may contain slight waves, slight crystallographic discoloration, and slight air inclusions and not more than one-half of the usable area.
V-4	Good Stained	Hard, of uniform color, may contain medium waves slight crystallographic discoloration, and medium air inclusion in not more than two-third of the usable area.
V-5	Stained A Quality	Hard, may contain medium air inclusions, uniformly distributed in the usable area; slight green vegetable stains, medium waviness, and heavy waves if specified.
V-6	Stained B Quality	Hard, may contain heavy air inclusions and heavy waves, medium green vegetable stains, slight black and red dots (mineral) and clay stains.
V-7	Heavy Stained	Hard, and may contain heavy air inclusions and waves, slight light black and red dots (mineral), medium cloudy stains, clay stains and green stains (vegetable). Soft, buckles, ridges, and sand blast acceptable if specified.
V-7A	Densely Stained	Hard and soft. May contain heavy waves and air inclusions, cloudy stains. High black and red dots (mineral). Medium black and red stained (mineral), buckles, and ridges. Also, green stain (vegetable type), clay stains, herringbones, and sand blast.
V-8	Black Dotted	Hard, may contain medium waves, heavy air inclusions, cloudy stains, light black and red dots (mineral), and green stains (vegetable).
V-9	Black Spotted	Hard, may contain medium waves, heavy air inclusions, cloudy stains, light black and red dots (mineral), and green stains (vegetable type), slight black stains (mineral), and sand blast.
V-10	Black Stained	Hard, may contain medium waves, heavy air inclusions, cloudy stains, light black and red dots (mineral), green stains (vegetable type), and sand blast, medium black stains (mineral), slight red stains (mineral), and clay stains.
V-10A	Densely Black and Red Stained	Hard, may contain heavy waves, air inclusion, cloudy stains, light black and red dots (mineral), red stains (mineral), black and red stains (mineral), green stains (vegetable type), and sand blast, very dense black and red stains (mineral), and slight clay stains. Soft if specified.