Refractory Application Procedure
REFRACTORY APPLICATION
PROCEDURE
OLD CO BOILR
HPCL VISAKH REFINERY
Refractory Application Procedure, 06.09.2021
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Refractory Application Procedure
1.
SCOPE
Refractory application in Old CO Boiler wherever it is required.
2.
PRE INSTALLATION ACTIVITIES
2.1 Obtain work permit
2.2 Existing castable lining to be removed in full thickness for that layer and
complete Anchor should be exposed for the area to be repaired.
2.3 Obtain mechanical clearance from HPCL. All mechanical work such as welding
of Anchor and any other mechanical, if any. should be completed prior to
refractory lining.
2.4 Ensure all workmen and supervisors are briefed about safety requirements,
instructions to be followed during emergencies.
2.5 Ensure/ arrange necessary safety gears for workmen and supervisors such as
safety shoes, helmets, gloves, safety belts (if working at heights), googles (for
welders), dust mask etc.
2.6 Check physical availability of the following materials:
a. Refralite – 9 Li , Insulating Castable - 5MT
b. Refratab-94, 94% alumina dense castable (Refratab 94)
2.7 Check following tools & machineries are available and in working condition:
a. Mixer
b. Masonary tools
c. Gunning machine
2.8 Arrange electric power and connections to work points for mixer and Gunning
machine.
3.
MIXING RATIO FOR CASTABLE & MORTAR
Following are recommended water % and mixing proportions for castables and
mortars used for the refractory lining. Water demand may vary to a reasonable extent
depending on site weather conditions.
Refractory Application Procedure, 06.09.2021
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Refractory Application Procedure
Brand Name
Refratab -94
Recommended Water % by
weight
10 to 12%*
Refralite – 9 LI
40 to 46%
*For gunning castables, the water % is controlled by gunman to achieve required
consistency of castable on the surface and cannot be checked physically.
4.
REFRACTORY APPLICATION IN OLD CO BOILER
4.1 Surface preparation/ coating
a. After anchor welding, clean inside casing thoroughly and remove all debris.
4.2 Formwork
a. Castable applications shall be made in panels, each panel shall be approx
1000mm by 1000mm. Panels to be cast in a staggered manner (first 1,3,5
positions and then 2, 4 etc.).
b. Formwork for (Refratab-94) shall be prepared and fixed in a manner to obtain
required castable thickness, length and slope as per drawing.
c.
Make wooden forms.
d. The form shall be fixed into position with adequate supports to prevent it form
displacing, while installing the castable.
e. The formwork is fixed at a distance, slightly greater than the thickness of
lining, from the shell plate, wooden or metal gauges can be used for this
purpose. The tolerance limit of lining thickness is -0 to +6mm.
f. No formwork is necessary for Insulating castable (Refralite – 9 LI)
applications as it is patch-up work applied by hand pack.
4.3
Mixing & placement of Refratab -94 Castable by gunning.
a) Clean the mixer and other material handling tools before mixing.
b) Use potable water for mixing of Castables.
c) Water at ambient temperature is required to expedite the setting time and avoid fall of
castable during gunning. Mixing temperature may go above 300C.
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Refractory Application Procedure
d) Pan mixer with adequate capacity shall be used for mixing of castable. Mixer
shall be thoroughly cleaned before use. If required, scrappers may be adjusted
to ensure uniform mixing and no accumulation of dry material at corners.
e) Pre dampen the dry castable by mixing with small percentage of water in a pan
mixer. Transfer the pre-dampened castable to the gunning machine.
f) Check connection of hose pipes, water and compressed air lines are OK for the
application. Ensure proper coordination between the nozzle-man at application
point and gun-man at discharge point regarding controlling of pressure/ release
of materials from machine etc.
5.1 Curing & formwork removal
a. Castables generally start setting after 3-4 hours of application. Setting is
indicated by warming of the formwork and/ or lining surface. Immediately
after the installed lining exhibits start of setting, curing shall be started and
continued for 24 hours.
b. Curing shall be done by covering the open surface/ formwork with wet jute
bags and sprinkling water time to time to keep the surface cool so as to
minimize loss of water from castable during setting. Side stoppers can be
removed after 2-4 hours depending on the setting behaviour of the castable.
Immediately after formwork removal, the surface shall be covered and curing
shall be done for 24 hours from application end point
c.
Check the lining for voids, if any. Small voids, if any (less than 1 inch dia)
may be filled with castable mix. In case of larger void, castable lining may
have to be locally repaired by breaking for full thickness and reapplying with
shuttering.
5.2 Application records for castable installation
Following records shall be maintained in suitable formats:
a.
b.
c.
d.
e.
Date of application
Batch number of castable
Manufacturing date/ expiry date whichever is available
Area of application (mention reference drawing number)
Quantity of materials used.
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