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pre-machined four way BOP castings with rough machining ZG25CrNiMo

Application: BOP,petroleum machinery
Weight: 500kg to 30 tons
Class certificate:ABS,CCS,NK,LR,DNV,RINA,BV,KR
Payment terms:T/T or L/C


Introduction To Pre-Machined Four-Way Blowout Preventer Castings

Steel GradeChemical Composition %

 Yield Strength

Rp0.2  /MPa

Tensile Strength

Rb / MPa


A / %

Reduction of Area

Z/ %


Normally we will follow 75K standard.

Prodution process

Equipment Name
1 Transformer substation 1
2 Full set of wooden molding equipment 10
3 Sodium silicate sand mix line 4
4 Alkaline phenol resin sand mix line 2
5 25 tons Electric arc furnace 1
6 50 tons Intermediate frequency furnace 2
7 120 tons Refining furnace 1
8 120 tons VD furnace 2
9 12m*9m*6m Heat treatment furnace 3
10 120 tons Large-scale shot blasting machine 1
11 150 tons Travelling crane 2
12 125 tons Travelling crane 3
13 200 tons Travelling crane 2
14 CNC gantry boring and milling machine 2
15 2.5m-10m Digital vertical lathe 16
16 Boring and milling machine 13
17 Horizontal lathe 3
18 Large dust removal equipment 7

1)The engineer will firstly prepare the technology and do a simulation before pouring.

pre-machined four way BOP castings

2)We will make a pattern of the four way based on engineer's technology.

It will cost us around one week.

After that the engineer will check the dimension and make a record.

The pattern will be reserved in our store within one year.

four way BOP castings

3)Sand molding making will be made by experienced wokrers.

The inner side will be painted and bured with fire for smooth and dry.

our maximum size pit is 87m*16m*(-3.5m),

the deepest pit is 45m*16m*(-6m).

For the big castings(within 150 tons) will always occupy more space and more time for cooling.

We should have well planed for them.

Sand molding

4)Pouring and cooling.

There are one 8tons electrical arc furnace;

Two 50 tons medium frequency furnace;

One 120 tons refining furnace and one 120 tons VD furnace;

Before and after pouring,we will do the chemical composition test.

Normally our raw material is from the same nearby supplier or some mature supplier.

If the requirement is high,such as low element of carbon,we will choose some better raw material.

5)Clean the sand and cut the riser after normalizing.

We cut the riser when it is hot.

6)Heat treatment will cost 7days( 4 days normalizing and 3 days tempring).

There are 8 heat treatment furances with max. one is 12m*9m*6m.

Heat treatment

7)dimension check and draw a line for machining.

After the castings are taken out from the steel box,we will check the dimension and do VT.

After rough machining and semi-finished machining,we are same doing the dimension inspection and making a record.

four way BOP castings

8)Rough machining

It is always 5-7mm margin left for each side.

The tolerance is up to the drawing or decided by customers.

Rough machining

9)NDT withe qualified inspector

NDT withe qualified inspector

10)Welding repair if needed and tempering for stress relief

11)Final machining and NDT

12)Customers' inspection and packing


About Haitai

Haian Haitai

Haian Haitai Casting Co.,Ltd. is established in 2003. 

We supply large steel castings with low carbon or alloy steel from 3 tons to 150 tons per piece.

With a quick development,now we had supplied steel castings 6,000 tons per month.

There are three workshop for sand mold making,one workshop for machining and one for post procedure.

We have rich experience to supply castings for BOP of Russian market.

Testing Equipment

Equipment Name Quantity(Set)
1 Sand analysis equipment 1
2 Impact sample low temperature meter 1
3 Direct reading spectrometer(OXFORD) 2
4 ONH analyzer 1
5 ZEISS metallurgical microscope 1
6 Pendulum impact tester 1
7 Microcomputer controlled electro-hydraulic servo universal test machine 5
8 Various hardness tester 4
9 Magnetic defect detector 5
10 Ultrasonic flaw detector(digital) 1
11 CX-52 Total station 1
12 Stylus roughness meter 1

We do the test according to diffrent production step,

such as chemical composition,UT,MT and mechanical property.

In 2021,Haitai inspection and testing center got approval from CNAS.





Our company is near to Shanghai port and we can supply different packing according to customers' specification.

Haian HaitaiHaian Haitai





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