[rambo]

Hi,

i just wanted some advice. I have 2 self designed and fabricated forging furnaces which go up to a max temp of about 1400'C. I use IS-8 Quality refractory bricks for lining the furnace walls and floor and have a mild steel door for the furnace. The door has ceramic fiber(coated with sodium silicate solution) lined in it to insulate and protect the 1 inch iron door. The Max capacity of the furnace is about 5 tons (depending on the size and shape of pieces being placed in it for heating).

My problem is that the bricks of the floor and arc(mouth of the furnace) as well as the door of the furnace does not last too long. every 2-3 months, 4 maybe if im lucky, the furnace needs to be repaired and the other furnace is taken into use. This is a major drain on my resources and repair time which could be used elsewhere is wasted here. Any suggestions on what i could use to help improve the life of the furnace. i will post the drawing of the furnace in a few minutes as soon as im done drawing it.

here we go, the drawing has been attached with the post.

 furnace0001.jpg (47.36K)
Number of downloads: 94  furnace0002.jpg (40.86K)
Number of downloads: 88


thanks and regards.

rambo

[forgemaster]

We use a water cooled door, have had it in use for about 4 years with not a problem. It is made from 75mm square hollow as heavy wall as I could buy. The SHS forms a watercooled rim around the outside, the middle is castable refractory. The water to cool the door is pumped in from a cooling tank placed outside. The connection is 1" gal pipe with heavy air hose to allow the door to lift up and down. Biggest problem we have is pumps stuffing up not the doors, we have replaced 2 pumps in 4 years, not bad seening as they run 24/7 I suppose.
If you want I could post some photos to assist with my description. The cooling tank is refilled by a ball cock.

Cheers
Phil

[ThomasPowers]

What did your refractory supplier suggest when you told him you were having this sort of problem? (Or contact the original manufacturer of the stuff as they should know what works best for your situation and be *happy* to keep you as a customer!

[rambo]

forgemaster, on 02 February 2010 - 05:03 AM, said:

We use a water cooled door, have had it in use for about 4 years with not a problem. It is made from 75mm square hollow as heavy wall as I could buy. The SHS forms a watercooled rim around the outside, the middle is castable refractory. The water to cool the door is pumped in from a cooling tank placed outside. The connection is 1" gal pipe with heavy air hose to allow the door to lift up and down. Biggest problem we have is pumps stuffing up not the doors, we have replaced 2 pumps in 4 years, not bad seening as they run 24/7 I suppose.
If you want I could post some photos to assist with my description. The cooling tank is refilled by a ball cock.

Cheers
Phil

dear forgemaster,

yes, that would be a big help in understanding how it is that this system works. what temperatures does your furnace reach? i would think that at 1300'C temperatures, which is the limit i work at, the water would evaporate instantly. could you give me a drawing of the door structure, inside the furnace and outside as well so that i can understand the same?

i appreciate your effort.

ThomasPowers, on 02 February 2010 - 12:01 PM, said:

What did your refractory supplier suggest when you told him you were having this sort of problem? (Or contact the original manufacturer of the stuff as they should know what works best for your situation and be *happy* to keep you as a customer!

well, the supplier had nothing to say.. both of them. they just stuck to their phrase that the quality of the bricks is not flawed. but even after explaining that im not playing the blame game, instead i want to know if there is something else they can recommend that i can use to increase my furnace life, they drew blanks. i even googled on the internet, but i cannot find anything which says, use such and such bricks made of this material. this will help increase ure furnace life as it can take so much more load, handles temp better etc etc.
so i thought i'd ask here at iforge. any help would be really appreciated. its a big drain on resources to have to build a 5 ton furnace every 2-3 months.

[ThomasPowers]

Yup; you need to switch refractory distributors/makers! Should be able to find one that will go all out for your business in this economic climate!

[forgemaster]

Hi Rambo
our furnace runs at about 1300c or there abouts, the water is pumped through the door rim by a 1" in 1" out 3 phase pump, our cooling tank is about 1300mm cube holds about 1.2 tonne of water. After a aussie summers day (42 deg C) the water would be at about 70 to 80 deg C, in winter we use it for hand washing. This is after 9 or so hours of running the furnace at full blast (1300C) After a days work I can still hold my hand on the door rim while the furnace is still going. I'll take a camera to work tomorrow and take some pickys.
For our floor we use a castable refractory specially designed for abrasive applications, it could also have stainless needles added to the mix if we needed it, to increase the wear resistance, I'll check out the bags tomorrow also and find out what it is.
Our opposition has been using this method for years with their doors and they still swear by it, even after going the kao wool packed door a couple of years ago, they still went back to the water cooled rim.

Phil

[OddDuck]

Rambo, does the stock that you are heating directly contact the floor of the furnace? Do you get scale or flux on it? At those temps iron itself is a pretty good flux and will help to break down the brick that the floor is made of. You may have to switch to a castable, possibly something magnesia based, think how they line crucibles and ladles and such in a steel works. The chemistry of the furnace atmosphere may be the part of the problem. The floor should be the coolest part of the furnace, so the temp rating may not be the problem. Is the damage to the door arch mechanical damage, say bumping stock into it? You might have to go with a harder brick in that location.
With all that said, there are some parts of the furnace that are probably going to have to be considered as "consumable", and will have to be replaced on a regular basis. I'm sure that the life can be extended between repairs, but nothing's perfect. If I were you, I would really analize what is causing the damage first, mechanical or chemical, and go from there.

[welder19]

I would switch to a different mfg or go with a high temp castable.

That's a BIG forge!

welder19

[forgemaster]

Have taken some photos.
I am having problems getting these to load, so I will try to load some more later tonight.
Basically these show our door with the water filled/cooled rim around it.
The pipes coming down through the hood, with heavy air hose to make a flexible connection to allow the door to go up and down.
The cooling tank outside, this is above the level of the door.
We use Plicast 60LC (LEB70544) for our furnace floor a castable refractory, we purchase it from a company called Vesuvius Australia. the product sheet gives it as "a low cement, high alumina castable with excellent strengths and outstanding abrasion resistance.
If you are using bricks on the floor which way are you laying them, sides flats or on end. On end is the better way to lay them.

Attached File(s)

•  Door.JPG (2.24MB)
  Number of downloads: 69
•  Pipes to hoses.JPG (2.45MB)
  Number of downloads: 73
•  Tank.JPG (2.03MB)
  Number of downloads: 39

[rambo]

Firstly i apologise for taking so long in replying. i was out visiting customers in diff cities so i couldnt get back to u guys.

OddDuck, on 05 February 2010 - 03:40 PM, said:

Rambo, does the stock that you are heating directly contact the floor of the furnace? Do you get scale or flux on it? At those temps iron itself is a pretty good flux and will help to break down the brick that the floor is made of. You may have to switch to a castable, possibly something magnesia based, think how they line crucibles and ladles and such in a steel works. The chemistry of the furnace atmosphere may be the part of the problem. The floor should be the coolest part of the furnace, so the temp rating may not be the problem. Is the damage to the door arch mechanical damage, say bumping stock into it? You might have to go with a harder brick in that location.
With all that said, there are some parts of the furnace that are probably going to have to be considered as "consumable", and will have to be replaced on a regular basis. I'm sure that the life can be extended between repairs, but nothing's perfect. If I were you, I would really analize what is causing the damage first, mechanical or chemical, and go from there.

yes ure rite.. it IS mechanical wear and tear. while loading of the stock in the furnace, the workers do bump the arc columns and the floor while placing the material inside. that isnt something that can be avoided a lot i guess cause of the sheer bulk of the raw material piece. still, i was thinking maybe i should go for some sort of ceramic fibre lining on the arc columns which would act as a cushion maybe?? but what kinda material mesh would be able to handle the temperature of the furnace to hold the fibre in place? a normal iron mesh would melt in seconds and let the fibre covering the columns fall in a heap.

welder19, on 05 February 2010 - 09:18 PM, said:

I would switch to a different mfg or go with a high temp castable.

That's a BIG forge!

welder19

lol well that depends actually. i know of my competitors having even bigger ones.

forgemaster, on 08 February 2010 - 02:09 AM, said:

Have taken some photos.
I am having problems getting these to load, so I will try to load some more later tonight.
Basically these show our door with the water filled/cooled rim around it.
The pipes coming down through the hood, with heavy air hose to make a flexible connection to allow the door to go up and down.
The cooling tank outside, this is above the level of the door.
We use Plicast 60LC (LEB70544) for our furnace floor a castable refractory, we purchase it from a company called Vesuvius Australia. the product sheet gives it as "a low cement, high alumina castable with excellent strengths and outstanding abrasion resistance.
If you are using bricks on the floor which way are you laying them, sides flats or on end. On end is the better way to lay them.

thanks for the upload forgemaster. hmm i also use a high alumina castable which is called IS-8 grade refractory brick. any idea how that compares with the one ure using?
my dad tells me that we've tried the water idea a few years back and it failed. could have been the design. the real prob is the sheet of cast iron which is covering the sides of the doors. at times the flame comes out through the sides and burns the place there, despite our putting heavier plates, its still something we need to repair regularly... maybe once in 2 months or so. in trying to think of a way that makes the door fit better in the furnace so that it fits tighter. its a door which is lifted open and close by a pulley system