Derrick Procurement: The 7-Point Checklist I Wish Someone Had Handed Me in 2017

Who this checklist is for (and why searching for it is a mess)

Search for "derrick" online and you'll get Derrick Henry's Hall of Fame case, Derrick Luckassen's transfer history, Derrick White's playoff numbers, a copy of The Very Hungry Caterpillar, somebody named Kendall, and a tutorial on how to get eyebrows. Not a single result about the steel lattice structure you're actually trying to buy.

That's the first thing nobody warns you about. The second thing nobody warns you about is that derrick procurement goes wrong in the same seven places almost every time — and nobody documents those places in one list.

So I'm going to. This is the checklist I built after nine years of handling derrick and rig structure orders, during which I personally made (and wrote down) six significant mistakes totaling roughly $47,000 in wasted budget. It has since caught 47 potential errors in the last 18 months.

Seven steps. Grab a coffee. If you're signing a PO in the next two weeks, read steps 1 and 5 at minimum.

Step 1: Confirm you're ordering a derrick, not a mast (this is where 30% of confusion starts)

People use "derrick" and "mast" interchangeably in conversation. In the spec sheets, they are two different structures with two different load paths.

Under API Spec 4F (Drilling and Well Servicing Structures), a derrick is a permanent, load-bearing structure that isn't designed to be raised and lowered as a unit. A mast is. A substructure is a third thing entirely, and it carries the rotary load, not the crown load.

I watched a buyer order a "derrick" against a spec sheet whose wind-load assumptions were written for a mast. Engineering ran the numbers on the wrong load case, and nothing fit when the steel landed. (This is the mistake I mentioned above where $890 in rework was the cheap part; the one-week schedule slip was the expensive part.)

Checkpoint: before you send an RFQ, get your engineering lead to initial the line that says structure type: derrick / mast / substructure. If it's a mix, break the RFQ into three line items.

Step 2: Pull the WPS / PQR package before you discuss price

Structural welding on a derrick falls under AWS D1.1 (Structural Welding Code — Steel), and the governing documents are the Welding Procedure Specification (WPS) and the Procedure Qualification Record (PQR).

Here's the thing vendors won't tell you: most of them will absolutely send you a WPS. What they won't volunteer is whether the WPS actually covers the plate thickness and joint configuration in your drawing.

In 2017, in my first year on this desk, I accepted a WPS package that was qualified on 1" plate. The actual joints in the shop drawing were 1.25". The shipment was rejected at the port, we paid for re-inspection, and the project slipped three days.

Checkpoint: compare every WPS against (a) plate thickness range, (b) welding process, (c) joint type (groove vs fillet), (d) position. If any one of those is out of range, the WPS is not applicable and the weld is technically unqualified — regardless of how good it looks.

Step 3: Match heat numbers on the MTRs, line by line

You want EN 10204 Type 3.1 material test certificates — that's the one where the manufacturer's authorized inspection representative independently verifies the test results, not just copies them.

A stack of 3.1 certificates proves something was tested. It doesn't prove the steel in the shipment is what was tested. That verification requires matching the heat number on each certificate to the heat number stenciled on the actual member.

I once approved a package with 14 MTRs on top and 11 actual heats on the steel, because two heat numbers were transposed between certificates 6 and 7. We caught it on-site during erection prep. $450 of re-tagging, one very awkward phone call, and a lot of lost credibility with the client's QA guy.

Checkpoint: ask for a heat-number cross-reference sheet, member by member. If the supplier can't produce one in under 48 hours, that's information — it means nobody in their QA flow has done this before.

Step 4: The load rating is a document, not a number on a placard

Everyone asks "what's the rated capacity?" Almost nobody asks for the certified load chart, the design wind speed assumption, and the derating factors.

API 4F ties wind load into the structural design, and the number on the nameplate usually reflects one specific configuration at one specific wind assumption. Change the wind zone, change the number. Add a top drive, change the number again.

Related equipment falls under API Spec 8C (Drilling and Production Hoisting Equipment) — worth confirming, since the crown block and travelling block ratings need to line up with the derrick's design load path, not just be individually certified.

Checkpoint: ask for the load chart, the design wind speed, the derating table, and the assumed dead-load + hook-load combination. If any of those four is missing, you're not buying a rated structure, you're buying a shape.

Step 5: Coating system and DFT — the step almost everyone skips until it costs them

This is the one. If you only remember one paragraph from this article, make it this one.

Most buyers write "painted" or "coated" on the spec and move on. The problem is that "painted" is not a specification — it's a hope. What you actually need to specify is:

• The ISO 12944 corrosivity category for the site. C3 for sheltered inland, C4 for industrial or coastal-with-shelter, C5 for direct coastal or high-humidity environments. Get this wrong and the coating is the first thing that fails.
• The coating system — primer, intermediate, topcoat, with product type and nominal DFT for each layer.
• The target total dry film thickness. As a rough ballpark (and I mean ballpark — check ISO 12944-5 for your exact durability class), C4 high-durability systems land around 240–320 μm, and C5 very-high-durability systems around 320–400 μm. Don't quote me in a contract, quote the standard.
• An inspection requirement — DFT gauge readings documented per member, plus holiday testing on critical surfaces.

In September 2022, on a twelve-piece order, we accepted "standard protective coating" as the spec line. Eight months later the client sent photos of rust bleed at every weld toe. We reshot-blasted and recoated eight of twelve members. I would rather not tell you the invoice total, but it was four figures and it embarrassed everyone involved.

The counterintuitive part: cheap coating rarely fails because it's cheap. It fails because nobody wrote down what "coated" was supposed to mean. Spend the hour. Write the spec.

Step 6: Specify how it gets shipped, not just what gets shipped

A derrick is a lattice structure designed to carry vertical and wind loads. It is not designed to carry its own weight in bending across a flatbed, which is exactly what happens when somebody skips the cradle.

Ask, in writing, for: lifting points and their rated capacity, bracing or cradle drawings, the tie-down scheme, and whether the structure is shipped assembled, partially assembled, or knocked down with match-marked joints.

Checkpoint: request the load-out drawing as a deliverable. If they can't produce one, they've never shipped a derrick that size.

Step 7: Close the document package before final payment — not after

The instinct is to chase documents at the end, when everyone's tired and the money's already moved. Flip it. Make the final 10% of payment conditional on receiving the full document package: MTRs with heat numbers, WPS/PQR set, load chart, coating inspection report, dimensional inspection report, and paint/certificate for any specialty fasteners.

The most frustrating part of this whole process is that the same gaps recur on every order — not because suppliers are lazy, but because nobody made the document list a payment condition. Once it's a payment condition, it stops being a favor and starts being a line item.

Common mistakes to watch for

• Quoting wind speed without a reference height. "Design wind speed: 100 mph" means nothing without the elevation and the exposure category. Ask for the reference.
• Accepting a nameplate capacity as the design capacity. They're different numbers. Always ask which one you're getting.
• Treating the shipping spec as logistics, not engineering. It's engineering. Cradle drawings exist for a reason.
• Skipping the coating spec because "it's just paint." It is not just paint. It's the line item that decides whether the client calls you in year two or year five.
• Assuming the first quote is the final scope. It's usually a starting position that assumes you won't ask for the load chart, the MTR cross-reference, or the coating DFT. Ask.

Client perception of your operation gets set in the first shipment, not in the brochure. A derrick that arrives square, tagged right, coated to spec, and documented cleanly tells the buyer exactly what kind of company they hired. The reverse is also true, and it's much harder to walk back.