Carbon Seal

Price: USD 1-1000

Carbon shaft seal has a long history. Graphite is an isoform of element carbon. In 1971, the United States studied the successful flexible graphite sealing material, which solved the leakage of atomic energy valve. After deep processing, the flexible graphite becomes an excellent sealing material, which are made into various carbon mechanical seals with the effect of sealing components. These carbon mechanical seals are used in chemical, petroleum, electric power industries such as high temperature fluid seal.

Because the flexible graphite is formed by the expansion of expanded graphite after high temperature, the amount of intercalating agent remaining in the flexible graphite is very small, but not completely, so the existence and composition of the intercalation agent have a great influence on the quality and performance of the product.

Selection of Carbon Seal Material

The original inventor used concentrated sulfuric acid as oxidant and intercalating agent. However, after being applied to the seal of a metal component, a small amount of sulfur remaining in the flexible graphite was found to corrode the contact metal after long term use. In view of this point, some domestic scholars have tried to improve it, such as Song Kemin who choosed acetic acid and organic acid instead of sulfuric acid. acid, slow in nitric acid, and lower the temperature to room temperature, made from a mixture of nitric acid and acetic acid. By using the mixture of nitric acid and acetic acid as the inserting agent, the sulfur free expanded graphite was prepared with potassium permanganate as oxidant, and acetic acid was slowly added to nitric acid. The temperature is reduced to room temperature, and the mixture of nitric acid and acetic acid is made. Then the natural flake graphite and potassium permanganate are added to this mixture. Under constant stirring, the temperature is 30 C. After reaction 40min, the water is washed to neutral and dried at 50~60 C, and the expanded graphite is made after high temperature expansion. This method achieves no vulcanization under the condition that the product can reach a certain volume of expansion, so as to achieve a relatively stable nature of the sealing material.

Specification of Carbon Ring Seal

Sealcon can produce different carbon ring seals according to different customers’ requirement.

model	M190T	M106K	M180K	M106D	M160C	M160B
material	pure graphite	furan resin	furan resin	antimony carbon	copper alloy	Babbitt alloy
density (g/cm3)	1.8	1.65	1.8	2.3	2.4	2.4
Fractural strength	100	65	80	65	80	65
(MPa)
compressive strength (MPa)	250	230	240	200	250	160
Shaw hardness	92	90	90	80	75	60
porosity (%)	1.2	1.5	1.2	2	2.5	8
Coefficient of heat	5.5	5.5	5.5	5.5	6	5.5
expansion (1/℃)
temperature (℃)	600	210	210	350	350	200

medium	concentration%	pure graphite	furan resin	antimony	copper alloy	Babbitt alloy
hydrochloric acid	36	+	0	-	-	-
sulfuric acid	50	+	0	-	-	-
sulfuric acid	98	+	+	-	-	-
nitric acid	50	+	0	-	-	-
nitric acid	strong		-	-	-	-
hydrofluoric acid	40	+	0	-	-	-
phosphoric acid	85	+	+	-	-	-
chromic acid	10	+	0	-	-	-
acetic acid	36	+	0	-	-	-
sodium hydroxide	50	+	+	-	-	+
potassium hydroxide	50	+	0	-	-	+
sea water		+	+	+	+	+
benzene	100	+	0	+	+	-
ammonia	10	+	+	+	+	-
acetone	100	+	+	+	0	+
carbamide		+	+	+	0	-
carbon tetrachloride		+	+	+	+	+
oil		+	+	+	+	+
gasoline		+	+	+	+	+