Ebonite lining

Bulk storage of 70% acid or greater may be in mild steel semi ebonite lined (without silica filler). Polyethylene, polypropylene, and PVDF are commonly used for construction of other major components. 

These same types of compounds are also more resistant to many acids at high temperatures than natural rubber can handle. Neoprene should not be used in parts which are bonded to metal for hydrochloric acid service because acid migration can cause failures. For hydrochloric acid service ebonite lined mild steel equipment is the correct selection. Ebonites form rubber hydrochloride film in contact with natural rubber and this film is the protective layer against corrosion. 

The electrolyser consists of a rectangular trough with a cover on top connected at both ends to the end boxes. The box at the mercury inlet is called the inlet box, and the other is the outlet box. The trough is of mild steel construction with ebonite lined bottom and sides. The covers are of mild steel construction with ebonite lining on the inside surface or only of rubber sheets called flexible cell covers. The covers have holes for fixing anodes. 

Figure 6.2b Autoclave curing cycle for ebonite lining...

Being more highly cross-linked, ebonite linings are even more resistant to swelling and permeation than soft rubber linings. However, they have to be vulcanized in woikshop autoclaves their use is generally restricted to relatively small items whose volume does not exceed about 100 m. ... 

Plant components of up to about 1000 m in volume can also be ebonite-lined on-site if hot water or piped steam is available for vulcanization. For adequate cross-linking, the steel must be heated to 90-95°C, which is only possible if effective exterior insulation is provided. The largest tank known to have been ebonite-lined on-site has a capacity of 8000 m. It has a triple-play lining, which was applied as a 5-mm-thick single sheet and consists of a soft rubber adhesive layer, a diffusion-proof ebonite layer, and a corrosion-resistant soft rubber layer. This tank has been continuously exposed to concentrated hydrochloric add containing chlorine and solvents withont suffering damage. 

Unless test coupons are produced alongside the lining, the only method of testing the vulcanisation state is with a hand hardness meter. A Shore A or IRHD meter is used for soft rubber linings and a Shore D meter for ebonites. The usual specification is that the hardness has to conform to 5° of the specified hardness. There is no quantitative non-destructive test for the strength of the bond between the lining and the substrate and so such tests are usually carried out in the laboratory on a sample prepared from the materials used. 

Ebonite is mainly used as chemically resistant plant linings. 

Rubber lining Rubber roll covering Tyre carcass Tyre tread Moulded tubes Footwear Soles and heels Mechanical goods Ebonites or hard rubber... 

It has been estimated that the consumption of rubber in ebonite products increased on an average of about 6% a year until 1951 when different plastics appeared in the market as competitive materials [6]. But because of the superiority of ebonites in acid and chlorine duties, it still maintains its place in the process industries as a material of construction as evidenced by its increased use in anticorrosive lining of chemical process vessels and tanks for the process industries and rolls for steel and textile and paper and pulp industries. 

A well compounded ebonite free from carbon black and hygroscopic ingredients and with its surface in a clean condition has a very high resistivity both through the mass of the material, and over its surface. It is so far above what is required for most practical purposes that it is seldom necessary to measure these properties, especially in cases of electroplating tanks lined with ebonite required in most steel plants. 

In open steam cure of linings and tubes and rods it is important that the ebonite does not flatten under self weight. Addition of ebonite dust and mineral fillers or reclaimed rubber increases the stiffness of the green stock and reduces the tendency for loss of shape. 

Chemicals, Chlor alkali. Paper and pulp, Fertilizers, Oil drilling and Pharmaceu ticals Chemical resistant linings for storage tanks, road and ship tankers, process vessels, pipelines, valves, pumps, filters, agitators, centrifuges, impellers, etc. Soft natural rubber or ebonite, neoprene, butyl and hypalon depending on operating temperature, and application. 

Marine Industry Corrosion resistant linings for fume scrubbers and cooling pipelines. Wear resistant linings for dredging pipelines. Ebonite or hard rubber for corrosion resistance. Soft natural rubber for wear resistance. 

Water and Effluent Treatment in Nuclear and other chemical plants. Corrosion resistant linings for water treatment vessels and pipelines, pumps, valves, flowmeters, agitators, chemical dosing tanks, effluent tanks etc. Soft natural rubber or ebonite, EPDM, butyl, neoprene or hypalon. 

Before an item of equipment lined with ebonite or any soft rubber leaves the workshop it is tested for non-porosity. According to regular practice, the only reliable method of determining this is that which makes use of a spark tester or inductor and a test voltage of 20,000 to 25,000 volts. For this purpose the spark tester or the inductor has been proved successful. 

Hot water cures can be used for articles that are not affected by immersion in hot water. This method is useful for thick walled articles and rubber lined equipment and especially most suitable for ebonite compositions. Direct contact with water produces better heat transfer than with hot air or steam. Consequently this system gives less deformation of products during cure. 

The calendering process and its conditions are developed or modified according to the requirements of subsequent operations and the purpose for which the sheet is used. Thus for sheets which are to be open cured, such as in chemical plant lining and custom built items such as inflatables and ebonite pipes, roll coverings for paper and steel mills, the calendering needs to be more exact than the sheets which are used for blank preparation for molding of... 

These filters were used in illmenite beneficiation and titanium dioxide plants. These and their parts like agitators, troughs etc., were lined with a semi-hard flexible ebonite of natural rubber to protect the equipment against the abrasive action of the ore and solid particles in the slurries. 

Exothermic - A chemical reaction in which heat energy is liberated. In tank linings, very thick layers of ebonite compounds may exotherm during cure. 

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