Detailed Understanding of Drilling Derrick Knowledge & Selection Guide

Key Takeaways for Procurement & Engineering:

• API Standard: Drilling derricks and masts strictly comply with API Spec 4F (Specification for Drilling and Well Servicing Structures).
• Derrick vs. Mast: Derricks are stationary, 4-legged lattice structures ideal for offshore platforms and deep land drilling; Masts are collapsible/cantilever units built for mobile land and workover rigs.
• Key Parameters: Load capacities range from 250,000 to 1,500,000+ lbs, with wind ratings up to 100+ knots.

Goldenman supplies drilling derricks and mast structures for land drilling rigs, offshore drilling rigs, and workover rigs. Our derricks can be configured according to rated hook load, derrick height, stand capacity, wind and environmental rating, substructure interface, rig floor layout, and project standards.

Available options include tower derricks, A-frame derricks, mast-type derricks, and K-type front-open derricks. Send your rig type, required hook load, height, wind rating, stand capacity, and destination country to get a technical datasheet, drawing, and quotation.

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I. Overview of derrick

A drilling derrick is the tall, load-bearing structure on a drilling rig used to support hoisting operations and handle drill pipe/casing stands. Key selection factors include rated hook load, height, wind rating, structural design, and compliance with required standards.

The derrick is one of the most visible symbols of the petroleum industry. It is a tower/mast-type steel structure used to place the lifting equipment and tools (such as crown blocks, traveling blocks, hooks, etc.), to withstand the heavy loads generated by drilling and casing running operations, and to provide the height and working space required for pipe string storage.

II. Drilling Derrick Classification

According to structural characteristics, drilling derricks are generally divided into the following four categories:

Type K Derrick (Front-Open Derrick)

Tower Type Derrick

Type A Derrick

Mast Type Derrick

Tower Type Derrick

The tower derrick is a space structure with four legs forming a truncated pyramid, typically with a square cross-section. This type of derrick generally utilizes a single-rod assembly structure, which requires significant time and high-altitude work during installation and disassembly. However, because it features a wide base support and a closed, integrated body, it offers excellent overall stability and massive load-bearing capacity. The tower derrick is one of the primary structural forms used on offshore drilling platforms.

Type A Derrick

It consists of two lattice or tubular legs connected with upper structural rods and the monkey board (second floor platform) to form an “A”-shaped space structure. With rectangular or triangular leg cross-sections, this type has good load capacity and stability. The sections are connected by pins; the derrick is assembled at a low position and raised into place by the winch using an A-frame or gin pole. Because the front and back remain open, the driller maintains an unobstructed view, which is why it is often called a “full-view derrick.”

Mast Type Derrick

The mast derrick is mainly used on mobile drilling rigs and workover rigs. It is a space structure composed of one or several sections of lattice or tubular legs. During operation, it inclines toward the wellhead direction by 3° to 8°, requiring guy lines (stretch ropes) to maintain stability. Mast-type derricks are divided into telescopic and non-telescopic types, with most workover and mobile rigs utilizing the telescopic design.

K-Type Derrick (Front-Open Derrick)

K-type derricks feature an open front face and a $\Pi$-shaped space truss cross-section. The sides are assembled or welded into several sections, while the back uses a truss rod system. Components are connected via heavy pins or bolts, allowing for low-level assembly and overall hydraulic or winch-powered erection. It offers excellent overall structural rigidity and can also be engineered as a telescopic derrick.

Quick Comparison: Drilling Derrick vs. Drilling Mast

To assist engineering teams in selecting the correct structural type, the key operational differences are summarized below:

Feature / Aspect	Drilling Derrick (Tower / K-Type)	Drilling Mast (Telescoping / Cantilever)
Structural Design	4-legged, stationary lattice tower or $\Pi$-shaped frame	Cantilever or telescoping single/multi-section column
Erection Method	Assembled piece-by-piece or lifted via hydraulic cylinders	Raised as a single pre-assembled unit via drawworks/hydraulics
Mobility & Transport	Fixed / semi-fixed; suited for extended deep drilling	High mobility; easily transported on trucks/trailers
Primary Application	Offshore platforms, deep land rigs, heavy drilling	Mobile land rigs, workover operations, shallow-to-medium wells
API Specification	API Spec 4F	API Spec 4F

III. Main Structure of a Drilling Derrick (K-Type Example)

Taking a K-type derrick without tension guy lines as an example, the main structural components include:

Derrick Accessories: Includes the standpipe/riser platform, casing centralizing platform, tong counterweights, and safety harness lines.nd equipment weight load, and transmits these loads to the foundation and foundation.

Derrick Body: Generally divided into 4 to 5 main segments connected by heavy pin shafts. The upper portion forms a quadrilateral closed frame, while the remaining lower sections utilize a front-opening structure. The rigid frame and oblique struts at the back are fully detachable.

Second Floor Platform (Monkey Board): Consists of the platform frame, operating area, finger beams, and inner/outer safety railings for pipe handling.

Cage Ladder: Installed on both sides of the derrick for operators to safely access the crown block platform and monkey board.

Lifting Device: Includes the lifting herringbone (gin pole), buffer cylinders, lifting wire ropes, and hoisting pulleys.

IV. Substructure (Base)

The base (substructure) is used to support drilling equipment (drawworks, rotary table, transmission units, diesel engines), store drill pipe and drill collars, support the derrick body, and provide working space for wellhead equipment and rig floor operations.

It absorbs all drilling loads, derrick lifting forces, and dead equipment weights, transferring these combined loads safely to the foundation.

1. Box stack base
2. Box block base (also called block mount base)
3. Rotary lift base
4. Slingshot base (also called double lift base)
5. Retractable base
6. The latter three are jack-up bases

V. Technical Specifications & Procurement Parameters

Use the following reference guide to define technical requirements when requesting project quotations:

Specification Item	Options / Technical Scope	Procurement & Project Notes
Rig Type Application	Land drilling rig, offshore platform, workover rig	Defines environmental coating & load rating requirements
Derrick Type	Tower, A-Frame, Mast, K-Type (Front-Open)	Selected based on mobility and space availability
API Standard Compliance	API Spec 4F (Latest Edition)	Industry mandatory standard for structural integrity
Rated Hook Load	250,000 lbs to 1,500,000+ lbs (1,100 kN – 6,700 kN)	Customized according to maximum planned drilling depth
Derrick Height	100 ft, 127 ft, 136 ft, 142 ft, 147 ft, 152 ft	142 ft and 147 ft accommodate triple pipe stands
Stand Capacity	Drill pipe / casing racking capacity	Configured to match drill floor setback layout
Wind Rating	85 knots (with pipe) / 100+ knots (bare structure)	Critical for coastal, Arctic, or desert environments
Substructure Interface	Rig floor, crown block, drawworks, setback area	Custom pin/bolt interface alignment
Material & Coating	High-strength structural steel, offshore anti-corrosion	Cold-weather steel (-40°C) options available

VI. Engineering Documents & RFQ Information

Engineering Documents Provided with Supply:

• General arrangement drawing
• Derrick structure & assembly drawing
• Substructure interface alignment drawing
• Structural load rating documentation
• Mill Material Certificates (MTR)
• Welding inspection report (WPS/PQR)
• NDT / UT / MPI inspection reports
• Surface treatment & anti-corrosion coating reports
• Packing, shipping, and sling installation manual

Drilling Derrick Price & RFQ Checklist

Drilling derrick pricing depends on derrick type, rated hook load, height, stand capacity, wind rating, rig floor layout, substructure interface, material selection, corrosion protection, inspection standards, quantity, and delivery destination. Goldenman provides project-based engineering quotations.

To receive an accurate technical quotation and general arrangement drawing, please specify:

1. Rig Type & Application (Land vs. Offshore)
2. Rated Hook Load & Derrick Height
3. Wind Rating & Operating Temperature
4. Substructure Interface Drawings (if available)
5. Destination Country & Lead Time Requirements

VII. Frequently Asked Questions (FAQ)

Q1: What API specification governs drilling derricks and masts?

A: Drilling derricks, masts, and substructures are designed and manufactured in strict compliance with API Spec 4F (Specification for Drilling and Well Servicing Structures), which governs load ratings, manufacturing tolerances, structural safety, and testing protocols.

Q2: What is the main structural difference between a derrick and a mast?

A: A derrick is a 4-legged, stationary lattice tower assembled piece-by-piece (or lifted in sections), providing maximum stability for deep land and offshore drilling. A mast is a cantilever or telescoping column raised as a single unit, offering rapid assembly for mobile land rigs and workover operations.

Q3: How do I choose between a K-type derrick and an A-frame derrick?

A: K-type derricks offer a front-opening design, high overall structural rigidity, and allow low-level assembly with hydraulic or winch raising, making them ideal for heavy land rigs. A-frame derricks provide excellent visibility for the driller and simple pin connections, making them suitable for medium-depth rigs.

Contact Goldenman

Contact Goldenman for technical selection and quotation.

Email: info@goldenman.com