1.9:1 elliptical head (Elliptical 1.9:1)
A slightly shallower version of 2:1 elliptical, to the French standard
The 1.9:1 elliptical head is defined by the French standard NF E 81-103 and has a diameter-to-depth ratio of 1.9 to 1; that is, slightly shallower than the standard ASME 2:1 elliptical head. Its crown radius is CR = Di/1.16 and its knuckle radius KR = Di/5.39.
What is a 1.9:1 elliptical head?
The 1.9:1 elliptical head is defined by the French standard NF E 81-103 and has a diameter-to-depth ratio of 1.9 to 1; that is, slightly shallower than the standard ASME 2:1 elliptical head. Its crown radius is CR = Di/1.16 and its knuckle radius KR = Di/5.39.
This type is mostly seen in projects whose design basis is European standards. Mechanically it differs little from the 2:1 elliptical head, but the reference design figures are calculated to NF E 81-103.
Geometry formulas of the 1.9:1 elliptical head
The formulas divide the inside diameter by the French standard's coefficients:
If the project requires European (especially French) specifications, staying with the 1.9:1 elliptical head makes sense; for an ASME basis, the 2:1 elliptical head has more reference sources.
Online calculation
See the head's dimensions, volume and weight for a real diameter and thickness
1.9:1 elliptical head (Elliptical 1.9:1)
Liquid level and volume inside this head
How the head is mounted
Development of this head (flat blank before forming)
The diameter of a flat plate of the same thickness and material that weighs the same as the formed head — an initial workshop estimate based on equal weight, not allowing for thickening or extra stretching at the knuckle.
The vessel head production process
From calculating the blank diameter to final edge preparation — the steps of making a vessel head in the workshop
Calculating the blank diameter
Cutting a disc from plate with the diameter and thickness calculated for the head type and vessel diameter
Cutting the plate blank
Precise cutting of steel or stainless plate by plasma, laser or gas according to the technical drawing
Pressing the head
Hot or cold forming of the disc with a die and industrial press until it reaches the final head profile
Edge preparation
Machining the edge, bevelling and preparing the weld area for fitting to the vessel shell
Video coming soonChoosing a head: the balance between pressure, cost and time
If your project requires European (especially French) technical specifications, or similar earlier equipment was built to this standard, staying with 1.9:1 elliptical makes sense. Otherwise, for projects with an ASME basis, 2:1 elliptical is the more common standard and has more reference sources.
Gallery of heads we have made
1.9:1 elliptical head gallery
Applications and industries served
Buying heads from Behineh Ab
Six steps from first contact to delivery
Give the outside diameter, plate thickness, head type and required material.
The calculated weight, unit price and delivery time are sent the same business day.
Plate is supplied with the mill certificate and inspected on arrival before cutting.
Cutting the disc, hot or cold pressing depending on thickness, and checking dimensions with a template.
Machining the cylindrical edge and bevelling it ready for welding to the shell.
Packing, issuing the part identification sheet and shipping nationwide.
What sets us apart
Price inquiry
vessel head
Enter the diameter, thickness and head type; you will receive the calculated weight and unit price.
- Quotation with the exact weight of the part
- Standard heads delivered in 7 business days
- Shipping nationwide
