{"id":2388,"date":"2026-06-30T08:59:01","date_gmt":"2026-06-30T08:59:01","guid":{"rendered":"https:\/\/hydrauliccylindersprice.com\/product\/electric-furnace-cover-lifting-cylinder\/"},"modified":"2026-06-30T08:59:08","modified_gmt":"2026-06-30T08:59:08","slug":"electric-furnace-cover-lifting-cylinder","status":"publish","type":"product","link":"https:\/\/hydrauliccylindersprice.com\/sr\/%d0%bf%d1%80%d0%be%d0%b8%d0%b7%d0%b2%d0%be%d0%b4\/electric-furnace-cover-lifting-cylinder\/","title":{"rendered":"Electric Furnace Cover Lifting Cylinder"},"content":{"rendered":"

<\/p>\n

<\/p>\n

\n
\n
\n Electric Furnace<\/span>
\n Cover Lifting Cylinder<\/span>\n <\/div>\n

The Rod Is 96% of the Bore.
This Is a Column, Not Just a Cylinder.<\/h2>\n

Bore 580 mm. Rod 560 mm. The rod fills nearly the entire bore \u2014 leaving just 10 mm of annular clearance per side. This is not a design error. The 560 mm rod is a structural column that holds the entire furnace cover overhead while scrap metal is charged into the furnace below. The hydraulics lift the cover; the rod holds it there.<\/p>\n

\n
\n
580mm<\/span><\/div>\n
Bore<\/div>\n<\/div>\n
\n
560mm<\/span><\/div>\n
Rod (96% of bore)<\/div>\n<\/div>\n
\n
3,448KN<\/span><\/div>\n
Thrust<\/div>\n<\/div>\n
\n
14MPa<\/span><\/div>\n
Lowest Pressure<\/div>\n<\/div><\/div>\n<\/p><\/div>\n<\/section>\n

<\/p>\n

\n

What Happens Inside an Electric Arc Furnace<\/h2>\n

An electric arc furnace (EAF) melts scrap steel using electric arcs \u2014 currents of 30,000\u201380,000 amperes jumping between graphite electrodes and the metal charge. The interior temperature reaches 1,600\u20131,800 \u00b0C. The furnace cover (roof) sits on top of the furnace shell, containing the heat, fume, and molten metal splash. The electrodes pass through holes in the cover.<\/p>\n

The cover must be lifted every time the furnace needs to be charged with fresh scrap metal \u2014 which happens 2\u20134 times per heat (each heat is one melt cycle, typically 40\u201370 minutes). The cover lifting cylinder raises the entire cover \u2014 typically weighing 20\u201380 tonnes including refractory lining \u2014 high enough for the charging bucket to swing over the open furnace and dump scrap into the shell. The cover is then lowered back into position for the next melt phase. This is the most extreme thermal environment any industrial engineering hydraulic cylinder<\/a> must survive.<\/p>\n

\"Electric
\n<\/section>\n

<\/p>\n

\n

Technical Specifications<\/h2>\n
\n\n\n\n\n\n\n\n\n\n\n\n\n
Parameter<\/th>\nValue<\/th>\n<\/tr>\n<\/thead>\n
Product<\/td>\nElectric Furnace Cover Lifting Cylinder<\/td>\n<\/tr>\n
Function<\/td>\nRaise and lower the furnace cover for scrap charging<\/td>\n<\/tr>\n
Bore Diameter<\/td>\n580 mm<\/td>\n<\/tr>\n
Rod Diameter<\/td>\n560 mm (96.6% of bore)<\/td>\n<\/tr>\n
Working Pressure<\/td>\n14 MPa (lowest in range)<\/td>\n<\/tr>\n
Maximum Thrust<\/td>\n3,448 KN<\/td>\n<\/tr>\n
Application<\/td>\nElectric Arc Furnace (EAF)<\/td>\n<\/tr>\n
Certification<\/td>\nISO 9001 \u00b7 100% hydrostatic tested<\/td>\n<\/tr>\n<\/tbody>\n<\/table><\/div>\n<\/section>\n

<\/p>\n

\n

Why the Rod Is 96% of the Bore \u2014 Hydraulic Actuator Meets Structural Column<\/h2>\n
\n \"Cover<\/p>\n

On a standard hydraulic cylinder, the rod diameter is typically 50\u201370% of the bore diameter \u2014 leaving substantial annular area on the rod side for retraction force. On this cover lifting cylinder, the rod is 560 mm in a 580 mm bore \u2014 leaving only 10 mm of annular clearance per side. This looks extreme, but it reflects the cylinder’s dual role.<\/p>\n

When the furnace cover is lifted, the entire weight of the cover \u2014 20\u201380 tonnes of steel shell and refractory lining \u2014 hangs from the cylinder rod. The rod must support this weight as a structural compression column without buckling. A 560 mm diameter solid steel rod has enormous column strength \u2014 far more than a standard 300 mm rod in a 580 mm bore would have. The rod is sized for structural column strength, not for hydraulic annular area.<\/p>\n

The working pressure is correspondingly low \u2014 14 MPa, the lowest in the Korea Ever-Power range. But the full bore area at 580 mm is 264,208 mm\u00b2, so even 14 MPa produces 3,448 KN of thrust \u2014 more than enough to lift the heaviest furnace covers. The design philosophy is: large bore for adequate force at low pressure, massive rod for structural integrity. The hydraulic function and the structural function are inseparable \u2014 this cylinder is as much a load-bearing column as it is a hydraulic actuator.<\/p>\n<\/p><\/div>\n

<\/div>\n<\/section>\n

<\/p>\n

\n

Surviving Beside a 1,800 \u00b0C Furnace<\/h2>\n

The cover lifting cylinder is mounted on the furnace support structure \u2014 typically within 2\u20135 metres of the furnace shell. During melting, the furnace interior reaches 1,600\u20131,800 \u00b0C, and the shell exterior radiates heat that raises the ambient temperature around the cylinder to 60\u2013120 \u00b0C. When the cover is lifted for charging, the open furnace exposes the cylinder to direct radiant heat from the molten metal bath. The cylinder must survive this environment for 15\u201320 years of service life.<\/p>\n

\n
\n Radiant heat shielding<\/strong><\/p>\n

The cylinder barrel and rod are protected by heat shields \u2014 steel plates with insulation backing \u2014 mounted between the furnace and the cylinder. These shields reduce the radiant heat reaching the cylinder surface from 600+ \u00b0C (unshielded) to under 80 \u00b0C (shielded). Korea Ever-Power designs the cylinder mounting with heat shield provisions as standard.<\/p>\n<\/p><\/div>\n

\n Water-cooled barrel option<\/strong><\/p>\n

For furnaces where heat shielding alone is insufficient (large EAFs, close-mounted cylinders), Korea Ever-Power offers a water-cooled barrel jacket \u2014 a welded-on cooling channel that circulates plant cooling water around the cylinder barrel, maintaining the barrel temperature below 60 \u00b0C even during extended melting campaigns.<\/p>\n<\/p><\/div>\n

\n Slag and metal splash protection<\/strong><\/p>\n

During charging, molten metal splash and slag particles can reach the cylinder. The rod is protected by a bellows boot or telescopic shroud that prevents hot particles from landing on the chrome surface. Any metal splash that contacts the rod would bond to the chrome and score the seal on the next stroke \u2014 a single splash event can cause a seal failure.<\/p>\n<\/p><\/div>\n

\n High-temperature seals and fluid<\/strong><\/p>\n

The cylinder uses FKM (Viton) seals rated for sustained temperatures up to 200 \u00b0C \u2014 well above the 80\u2013120 \u00b0C that the shielded cylinder surface experiences. The hydraulic fluid is a high-VI (viscosity index) mineral oil or fire-resistant fluid (HFC or HFD) selected to maintain viscosity at elevated operating temperatures.<\/p>\n<\/p><\/div>\n<\/p><\/div>\n<\/section>\n

<\/p>\n

\n
\n

The Cover Lift Cycle \u2014 60 Seconds That Cannot Fail<\/h2>\n

The cover lift is one of the most time-critical operations in EAF steelmaking. Every second the cover is open, the furnace loses heat (wasting energy and extending the melt time) and exposes the melt shop to fume and radiant heat. The cylinder must lift fast, hold reliably, and lower smoothly \u2014 with zero tolerance for malfunction.<\/p>\n

\n
\n Lift (10\u201320 seconds)<\/strong><\/p>\n

The cylinder extends, raising the cover to full height. Speed must be fast enough to minimise heat loss, but controlled enough to prevent the cover from swinging or oscillating. A load-holding valve locks the cylinder at full extension \u2014 the cover must stay up without pump pressure while the charging bucket swings into position.<\/p>\n<\/p><\/div>\n

\n Hold + Charge (20\u201340 seconds)<\/strong><\/p>\n

The charging bucket, loaded with 30\u201360 tonnes of scrap steel, is positioned over the open furnace and dumped. The cover cylinder holds the cover motionless throughout \u2014 the bucket swing, the dump impact, and the vibration from scrap hitting the furnace shell must not affect the cover position.<\/p>\n<\/p><\/div>\n

\n Lower (10\u201320 seconds)<\/strong><\/p>\n

The cylinder retracts, lowering the cover onto the furnace shell rim. The final 50 mm of descent must be slow and controlled \u2014 the cover must seat precisely on the furnace rim seal without impact. A hard landing damages the refractory lining on the cover’s underside and can crack the seal ring. Contact the hydraulic cylinder engineering team<\/a> for cover lift cycle time specifications.<\/p>\n<\/p><\/div>\n<\/p><\/div>\n<\/p><\/div>\n<\/section>\n

<\/p>\n

\n \"Electric
\n<\/section>\n

<\/p>\n

\n

Manufacturing for Extreme-Temperature Service<\/h2>\n
\n \"Korea<\/p>\n

The 580 mm bore and 560 mm rod create a unique machining challenge: the rod guide bearing and seal gland must maintain precise concentricity over a 560 mm diameter \u2014 any eccentricity causes the massive rod to load the seals unevenly, accelerating wear on one side. Korea Ever-Power machines the rod gland bore on CNC equipment with verified concentricity to the barrel bore within 0.1 mm total indicated runout.<\/p>\n

The 560 mm rod is forged, rough-machined, stress-relieved, finish-ground, and chrome plated (80\u2013100 \u00b5m for EAF service). The straightness is critical \u2014 at 560 mm diameter and column-loading duty, even 0.5 mm of bow concentrates stress on one side of the guide bearing during the structural hold phase. Rod stock is verified for bow \u22640.2 mm\/metre before chrome plating.<\/p>\n

Every cover lifting cylinder is hydrostatic tested at 1.5\u00d7 working pressure (21 MPa) with a sustained hold test. For EAF customers, Korea Ever-Power also performs a structural load test \u2014 applying the rated cover weight to the extended rod and verifying zero deflection and zero pressure drop during a simulated hold period.<\/p>\n<\/p><\/div>\n

<\/div>\n<\/section>\n

<\/p>\n

\n

OEM & ODM<\/h2>\n
\n
\n
\n

What You Provide<\/h3>\n<\/div>\n
\n

Furnace cover weight (tonnes including refractory), lift height, lift\/lower speed requirement, distance from cylinder to furnace shell (for thermal analysis), cooling water availability (for water-cooled jacket option), mounting geometry, and the furnace support structure drawing. For replacements: existing cylinder dimensions and the original furnace GA drawing.<\/p>\n<\/div><\/div>\n

\n
\n

What the Factory Delivers<\/h3>\n<\/div>\n
\n

Engineering drawing with bore, rod (column-strength verified), stroke, thermal protection specification (heat shield or water-cooled jacket), seal and fluid specification for the thermal environment, rod shroud detail, and load-holding valve provisions. Hydrostatic + structural load test certificate. Seal kits. Browse all industrial engineering hydraulic cylinders<\/a> including the full electric furnace cylinder family.<\/p>\n<\/div><\/div>\n<\/p><\/div>\n<\/section>\n

<\/p>\n

\n

FAQ<\/h2>\n
\n
\n

Why is the working pressure so low (14 MPa) compared to other cylinders?<\/h3>\n

Because the bore is large (580 mm) and the required force is moderate (3,448 KN \u2014 lifting a furnace cover, not forging steel). At 580 mm bore, even 14 MPa produces adequate thrust. Lower pressure also means lower stress on the barrel walls and seals \u2014 extending service life in the high-temperature EAF environment where seal ageing is already accelerated by heat. Higher pressure would not help and would reduce the reliability margin.<\/p>\n<\/p><\/div>\n

\n

What other cylinders are on the electric furnace?<\/h3>\n

A complete EAF uses up to six cylinder types: cover lifting (this product), cover rotating (swings the cover aside after lifting), tipping (tilts the furnace for tapping molten steel), electrode lifting and mast (raises and lowers the graphite electrodes), and lock cylinders (secure the cover in position). Korea Ever-Power manufactures the complete electric furnace cylinder set<\/a> \u2014 all six types engineered for the same furnace’s thermal environment.<\/p>\n<\/p><\/div>\n

\n

Can fire-resistant hydraulic fluid be used?<\/h3>\n

Yes \u2014 and many EAF installations require it. HFC (water-glycol) and HFD (synthetic ester) fire-resistant fluids are compatible with the cover lifting cylinder. The seal specification is adjusted for the specific fluid chemistry (HFC fluids are water-based and require different seal compounds than mineral oil). Korea Ever-Power specifies the seal material based on the fluid type \u2014 inform the engineering team of the planned fluid when ordering. The same fluid-compatibility engineering applies across the full hydraulic cylinder product range<\/a>, including forklift cylinders<\/a> and telescopic cylinders<\/a>.<\/p>\n<\/p><\/div>\n<\/p><\/div>\n<\/section>\n

<\/p>\n

\n

Related Categories<\/h2>\n
\n <\/p>\n
\n
\"Telescopic\"<\/div>\n
\n
Telescopic Hydraulic Cylinders \u2192<\/div>\n
Dump truck, trailer, hoist.<\/div>\n<\/div>\n<\/div>\n

<\/a>
\n <\/p>\n

\n
\"Forklift\"<\/div>\n
\n
Forklift Hydraulic Cylinders \u2192<\/div>\n
Lift, tilt, steer \u2014 OEM.<\/div>\n<\/div>\n<\/div>\n

<\/a>
\n <\/p>\n

\n
\"AWV\"<\/div>\n
\n
Aerial Work Vehicle Cylinders \u2192<\/div>\n
Scissor, boom, platforms.<\/div>\n<\/div>\n<\/div>\n

<\/a>\n <\/div>\n<\/section>\n

<\/main><\/p>","protected":false},"excerpt":{"rendered":"

Electric furnace cover lifting cylinder \u2014 the actuator that raises and lowers the roof of an electric arc furnace (EAF). This is no ordinary cylinder. The rod diameter is 560 mm \u2014 96% of the 580 mm bore \u2014 making the rod a near-solid structural column that supports the multi-tonne furnace cover at full height. Working pressure is just 14 MPa (the lowest in the Korea Ever-Power range), but the bore is large enough to generate 3,448 KN of thrust at this modest pressure. The cylinder operates beside a furnace whose interior reaches 1,600\u20131,800 \u00b0C \u2014 the most extreme thermal environment of any industrial hydraulic cylinder. Korea Ever-Power. ISO 9001. OEM & ODM.<\/div>","protected":false},"featured_media":2389,"comment_status":"closed","ping_status":"open","template":"","meta":{"_et_pb_use_builder":"","_et_pb_old_content":"","_et_gb_content_width":""},"product_brand":[],"product_cat":[852],"product_tag":[],"class_list":["post-2388","product","type-product","status-publish","has-post-thumbnail","product_cat-industrial-engineering-hydraulic-cylinders","pa_editor-cxm","first","instock","product-type-simple"],"_links":{"self":[{"href":"https:\/\/hydrauliccylindersprice.com\/sr\/wp-json\/wp\/v2\/product\/2388","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/hydrauliccylindersprice.com\/sr\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/hydrauliccylindersprice.com\/sr\/wp-json\/wp\/v2\/types\/product"}],"replies":[{"embeddable":true,"href":"https:\/\/hydrauliccylindersprice.com\/sr\/wp-json\/wp\/v2\/comments?post=2388"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/hydrauliccylindersprice.com\/sr\/wp-json\/wp\/v2\/media\/2389"}],"wp:attachment":[{"href":"https:\/\/hydrauliccylindersprice.com\/sr\/wp-json\/wp\/v2\/media?parent=2388"}],"wp:term":[{"taxonomy":"product_brand","embeddable":true,"href":"https:\/\/hydrauliccylindersprice.com\/sr\/wp-json\/wp\/v2\/product_brand?post=2388"},{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/hydrauliccylindersprice.com\/sr\/wp-json\/wp\/v2\/product_cat?post=2388"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/hydrauliccylindersprice.com\/sr\/wp-json\/wp\/v2\/product_tag?post=2388"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}