Valve cost

[samsarani]

Dear friends

One of big issues for me in oil and gas projects is estimating price of valves especially ball valves ( manual , MOV,ESDV,...). I know the best method is getting budgetary price from manufactures, but as you know some manufactures are careless in giving precise price in budgetary stage. We have some information and data from last projects but it can't cover all size and all classes. Then I need to have some engineering guesses for two following case.
1- effect of class of ball valve on price of it for example I have price of ball valve 8 inch class 1500 but I want to reach 8 inch class 900 with the same specification and materials.
2- effect of size of ball valve on price , for example I have price of ball valve 8 inch class 1500 and I want to obtain price of 10 inch ball valve class 1500 with the same specification and material

Thanks all

 

[gerhardl]

The more systematic and 'realistic' your guesstimates are, the more you will be helped by the law of averages. That is: if you can manage to spread your guestimates on both sides of the real value, neither systematically below nor systematically above the real market price, the better your average result will be.

Three simple ways to guess better:

1. Start telling yourself: the item can in my experience impossibly not cost less than x, and impossibly not more than y. Guesstimated price: (x+y)/2. (This is surprisingly accurate for the sum of a larger number of posts, if you have some pricing experience and data for the items to base your guesstimates on)

2. Use a simple, even hand drawn, graphic curve, for similar items. Here for instance curves for known prices versus sizes for the two pressure classes. Then estimate visually where the missing item should be placed on the price / size-curve. Alternatively: estimate or calculate differences in percentages.

3. Use preliminary, updated prices as help to figure out point 1 and 2.

Note: Price related to size and pressure class might have different sized steps and jumps for different classes, different sizes and might vary from producer to producer as well as from valve-type to valve-type.

4. Any cost calculus should be added to with a separate post item (for the total added sum, not for each single post)for uncertainty (or unintentionally left out costs), say 2 - 7%.

Good luck!