Types of ellipsoidal heads-HHA, EHA, EHB, THA, THB, SDH

The customer order description is EHA DN400x8 ellipsoidal heads GB/T25198-2010 Grade:Q345R.It is clear that the standard for the ellipsoidal head is GB/T25198-2010,and the customer needs the EHA type ellipsoidal heads.

So below i will introduce the types of ellipsoidal head in the GB/T25198-2010 standard.It is mainly divided into following types:

HHA type ellipsoidal head

HHA type ellipsoidal head

1. Hemispherical head (HHA);

EHA type ellipsoidal head

EHA type ellipsoidal head

 

EHB type ellipsoidal head

EHB type ellipsoidal head

2. Elliptical head,elliptical head including ① (EHA) based on internal reference,② (EHB) based on outside the standard;

THA type ellipsoidal head

THA type ellipsoidal head

 

THB type ellipsoidal head

THB type ellipsoidal head

3. Ellipsoid shaped head,including ①(THA) based on internal standards,② (THB) based on outside the standard;

SDH type ellipsoidal head

SDH type ellipsoidal head

4. Spherical crown head (SDH).

According to the description of customer provide with the corresponding drawing,it is not difficult to see that the size of DN400x8corresponds to D1 and  h,then H can be calculated according to the formula,H = D1/4 + h. In the figure,σ is not a fixed value,in the standard of GB/T25198-2010,there is a special description of the σ value.The value of σ is related to the tolerance of the outer circumference and inner diameter of the ellipse head.

For example,the nominal diameter DN is between 300-600,when 2≤σ≤4,the outer circumference tolerance is -4~+4,the inner diameter tolerance is -1.5~+1.5;when 4≤σ≤6,the corresponding tolerance are -6 ~+6 and -2~+2;when 6≤σ≤16,the corresponding tolerance are -9~+9 and -3~+3;when 16≤σ≤22,the corresponding tolerance are -12~+12 and -4~+4.

If you want to know more about ellispoidal head and other pipe fittings,flanges products,you can feel free to contact us email: sales@haihaogroup.com

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