coke oven patcher Interview Questions and Answers

1. What is a coke oven?

   • Answer: A coke oven is a large, brick-lined chamber used in the coking process to convert coal into coke, a fuel used in the iron and steel industry. The process involves heating coal in the absence of air to drive off volatile compounds, leaving behind a porous carbon material.

2. Describe the patching process in a coke oven.

   • Answer: Patching involves repairing damaged areas of the coke oven's refractory lining. This typically involves removing damaged bricks, cleaning the area, applying a patching material (often a refractory mortar or castable), and allowing it to cure before the oven is returned to service. The specific procedure depends on the extent and location of the damage.

3. What are the common types of damage found in coke oven walls?

   • Answer: Common damage includes spalling (chipping or flaking of the refractory), erosion (wearing away of the refractory), cracks, and holes. Damage can be caused by thermal shock, chemical attack, abrasion, and mechanical stress.

4. What safety precautions are crucial when patching coke ovens?

   • Answer: Crucial safety precautions include wearing appropriate PPE (personal protective equipment) such as respirators, hard hats, safety glasses, and protective clothing; using proper fall protection; following lockout/tagout procedures to prevent accidental energization; and adhering to confined space entry protocols if working inside the oven.

5. What are the different types of patching materials used?

   • Answer: Common patching materials include refractory mortars (air-setting or chemically-setting), castables (which are poured and set), and pre-cast shapes. The choice depends on the severity of the damage, location, and operating conditions.

6. How is the success of a patch measured?

   • Answer: Patch success is measured by its durability, resistance to further damage, and its ability to prevent leaks and heat loss. This is often assessed through visual inspections, thermal imaging, and leak detection tests.

7. Explain the importance of proper surface preparation before patching.

   • Answer: Proper surface preparation is crucial for ensuring a strong bond between the patching material and the existing refractory. This involves removing all loose or damaged material, cleaning the surface of dust and debris, and potentially applying a bonding agent to improve adhesion.

8. What tools and equipment are commonly used for coke oven patching?

   • Answer: Common tools and equipment include pneumatic chipping hammers, drills, grinders, mixing equipment for mortars and castables, scaffolding, and various hand tools for cleaning and shaping the patch.

9. What are the common causes of coke oven refractory damage?

   • Answer: Causes include thermal shock (rapid temperature changes), chemical attack from coal constituents and byproducts, abrasion from the movement of coal and coke, and mechanical stress from expansion and contraction during heating and cooling cycles.

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