FIELD OF INVENTION
The present invention relates to development of a method for easy and a fool-proof
fit-up of hemi-heads with nozzle without using backing plates for high pressure high
temperature OTSC boiler.
BACKGROUND & PRIOR ART OF THE INVENTION
For fit-up and welding of the nozzle with hemi-heads of Separator vessels, backing
ring is normally used which shall be removed after welding. This method is not a
fool proof one and more distortion shall occur during welding. Machining of
Seperator Vessels Dished end is done by providing a step which acts as backing
plate for nozzle welding.Once welding is completed the step portion shall be
removed by machining. Thus by this project the backing plate is completely avoided.
OBJECTS OF THE INVENTION
It is therefore the object of invention is to propose development of a method that
shall aid easy fit-up of nozzle with hemi-head.
Another object of invention is to discard backing plates used for fit-up of the nozzle.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The invention is described with the help of Figures 1 to 6, where:
Figure 1 is a schematic arrangement which shows conventional design which
involves a backing ring for fit-up of hemi-head and nozzle.
Figure 2 is a schematic arrangement of modified design of hemi-head.
Figure 3 is a schematic arrangement of modified design of nozzle.
Figure 4 is a schematic arrangement which shows the fit-up of nozzle with
Hemi-head.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE
INVENTION
Hemi-head with nozzle welding in Vertical separator of OTSC boiler is a critical
activity which requires precision as well as good quality. After completion of the
welding and corresponding NDE of the weldment, the assembly of Hemi-Head with
nozzle shall be welded with the main assembly of the Vertical Separator.
Fit-up of Nozzle with Hemi-head was being done by using a backing ring made of

the same material as the nozzle. The backing ring has to be initially welded with the
Hemi-Head, only after which the nozzle can be fitted-up. It has been a time
consuming process involving more man power and crane dependency for
adjustment of height.
The modified design of the Hemi-head and the nozzle aids in fool-proof fit-up as well
as eliminates the use of backing ring completely. The hemi-head is provided with a
projection inside in machining which acts as an integrated backing ring. The taper
provided in the hemi-head is same as the step-turned portion in the nozzle, thus
providing proper seating during assembly.
The modification in the machining of the hemi-heads as well as the nozzle results in
reduction in cycle time and manpower.
Prior to this invention a backing ring ( 03) was needed to be welded to the
hemisphere head (1) over which the nozzle (02) had to be fitted up as shown in Fig.
1. The process is time consuming and error prone due to welding contraction and
fitting of the nozzle due to dimensional variation and tolerance level.
The present invention proposed certain modification of the hemisphere head (04)
and the nozzle (05), wherein the hemisphere head (04) is provided with stepped
projection (06) inside as an integrated backing ring, substituting the old method and
design.

The taper (06) provided in the hemi-head (04) is same as step-turned portion (07)
of the nozzle (05), carried out by step turning of the nozzle (05) for proper seating
of nozzle with hemi-head. The stepped turned nozzle is made to seat on the
projected ring before welding and the same is welded after proper alignment.

WE CLAIM
1) A method of nozzle welding in hemisphere head (04) of a separator for OSTC
boiler, wherein,
- the hemi-sphere head (04) provided with stepped projection (06) as an
integrated backing ring;
- the nozzle (05) having stepped turned portion (07) is made to seat upon the
projected ring (06), properly aligned;
- the mating portion of the hemisphere ring and taper nozzle welded to form a
composite unit.

2) A welded composite unit (08) for vertical separator of OSTC boiler comprising,
hemispherical body (04) and nozzle (05).
3) The composite unit as claimed in claim 2, wherein the hemisphere head (04)
having a stepped projection as an integrated backing ring (06) allowing the
nozzle to seat over it.
4) The composite unit as claimed in claim 2, wherein the nozzle (05) having a
stepped turn portion (07) for seating upon the backing ring (06) having matched
dimensionally for mutual mating surface.