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DELATITE vs VALVE TECHNOLOGIES

1:  Delatite have a repairable and replaceable sealing seat.

Parts are readily available and at the time of writing this document not one valve repair kit has been sold.The only parts to be sold have been 2 off packing sets.

Valvetechnologies (VTI) have an integral seat machined into one half of the valve body.

If you have an integral seat and the seat is damaged beyond a simple light lap the half of the valve that contains theseat has to be replaced.

2: Seat Materials and Coating

Delatite use 431 stainless steel and coat it with LLK 1906 for all valves regardless of body material. The only timethis would change if there was a special material requirement to meet the customer needs.

Body in A105 A182 F22 and A182 F316 all have the same trim material. The expansion rate for 431 SS and LLK1906 is the same so you eliminate the cracking that occurs due to thermal expansion and contraction.

If you have an integral seat, a change in body material and maintaining the same coating could cause the coating to

crack due to the different expansion rates of the body material and the coating material.

A105, A182 F22, and A182 F316 all have different expansion rates but are coated with the same carbide.

3: Guilds

Delatite have 2 well spaced guilds to support the valve stem.One in the body and the other in the valve bracket. There is also a stem thrust bearing.

The stem of the VTI valve is very short and they require a stem adaptor to be fitted to all valves. The drive shaft ofthe VTI valve is not one piece and solid and there is room for side movement when the valve is operated.

As the guiding of the stem in this design is limited to one guide any sidewards movement of the stem can cause the

 packing to be compress or relaxed on one side of the packing box causing premature packing failure.

4: BracketThe Delatite valve has a very solid precision machine bracket which include a stem guide for greater stem support and

stem to actuator alignment.

5: Packing 

Delatite use 4 coils 2 x woven and 2 x solid.

Bellville disc spring maintain pressure on the gland flange and in turn maintaining the correct pressure on the packingthis is often referred to as a live loading.

VTI use 3 coils 2 x woven 1 x solid

And a similar live loading is used but 3 coils are not as good as 4 coils.

6: Lapping of Ball and Seats 

Delatite lap both sides of the ball to the sealing seat.VTI only lap one side of the ball to the sealing seat.

7: Seat Leakage

Delatite valve meet or exceed MSS SP.61 for block valves.VTI valve conform to ANSI class V or VI.

The problem is that the ANSI class is a control valve leakage class and class VI is for a soft seated control valve.

MSS SP.61 is a block valve standard.The VTI is not a control valve so why use the ANSI Control valve class?Delatite have supplied valves using Helium as the test gas. The outcome is Bubble tight for the duration of the test

on all valves.

8: Spare Parts

If required spare parts are readily available and at a price which makes repairing the valve a very viable option.

9: The valve bracket is precision machined and fitted to a machined surface on the valve.

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10: Valve Construction

Pressure Rating ANSI 3200#.Stem very large diameter precisely guided at both ends for maximum rigidity.

Large stem drive flats to engage the ball and double D to engage the actuator or lever.Blow out proof stem.

Oversized split collar fitted to the oversize stem are held captive in a recess machined into the valve body.

The split collar (retainer) is not involved in driving the valve open or closed. The sole purpose of the split collar

is stem blow out prevention.

Body Gasket

Oversized body gasket which is located away from the valve seating area.The gasket is a metal wedge ring type which is used in all Delatite Ball Valves and has a proven record for beinga very reliable means of sealing the two body halves.

Special Materials

Delatite Valves are available in any body material that meets the customers pressure Temperature Corrosion and

Erosion requirements.

Special coatings are also available to meet customer requirements.

Warranty

Tight Shut off to MSS SP.61 for 4 years.

This does not include leakage due to mechanical damage or damage caused due to the valve not beingclosed correctly.

The reason Delatite use a replaceable seat are that it make’s the valve more suitable for repair.All it takes to make sure you have no leakage around the back of the static seat is a little extra care when machining

the valve body and seat.As for VTI, the easy way out is to have an integral seat. But the advantages of the integral seat are outweighed by

the benefits of the replaceable seat.

The upstream seat of the Delatite Valve is 431 Stainless Steel coated LLK 1906.

In the VTI upstream seat it is the same as the body material and only hard faced.If the VTI valve fails due to seat leakage from seat damage which can not be lapped out, you must replace;

1 

Body Half2  Ball3  Seat

4  Bellville spring5 

Packing

6 

Body Gasket

7  Live load springs

At spare part pricing and labour costs it is cheaper to throw the valve away and buy a new one

As High Pressure Valves are not Cheap Delatite’s policy is for the customer to get as much service life out of eachvalve as possible. This includes the ability to repair the valve at an economical cost and return it to as new condition.