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Essential Guide to Drill Pipe Procurement: An In-Depth Overview of API 5DP, API 7‑1, NS‑1, and GOST Certification Systems
Author:
WHH
Source:
LONGWAY
Published:
2026-09-21
In the procurement and technical selection of drill pipes, standards and certifications represent indispensable foundational requirements. However, confronted with a host of standard designations—such as API 5DP, API 7‑1, ISO 11961, NS‑1, GOST, and others—many procurement and technical professionals remain unclear about the distinctions and interrelationships among them. This article systematically reviews the major international standards and certification systems in the drill pipe sector, helping you swiftly establish a clear framework of understanding.
I. Overview of the Drill Pipe Standardization System
Drill pipe From manufacturing to use, the relevant standards can be categorized into three levels:
| Hierarchy | Standard Type | Representative standard | Function |
| Product Standard | Specifies the manufacturing requirements for the drill pipe itself. | API 5DP, ISO 11961 | Steel grade, size, thread, inspection |
| Component Standard | General requirements for drillstring components | API 7-1, ISO 10424-1 | Drill collars, heavy-weight drill pipes, and square drill pipes |
| Certification system | Verify the manufacturer’s quality system | API Q1, ISO 9001, NS-1, GOST | Factory audit, product certification |
II. API 5DP: The Core Product Standard for Drill Pipe
API 5DP (Specification for Drill Pipe) is a drill pipe–specific standard issued by the American Petroleum Institute and is the most frequently cited standard in global drill pipe procurement.
Scope of application: Steel drill rods with thickened tube ends and welded tool joints.
Core content:
Steel grades: E75, X95, G105, S135, V150, and the SS sulfur-resistant series.
Dimensions: 9 standard outer diameters ranging from 2-3/8″ to 6-5/8″.
Product Specification Levels: PSL-1, PSL-2, PSL-3
Connection threads: NC, REG, FH, IF
Inspection requirements: 100% non-destructive testing and mechanical property testing.
2025 Update: Supplement No. 1 to API 5DP, Second Edition, was published in January 2025 and entered into force on July 2, 2025. Key changes include a maximum weld hardness limit (E/X/G/S ≤ HRC 37; SS ≤ HRC 32), a minimum grain size of ≥ ASTM Grade 6 for SS steel grades, and a martensite transformation rate exceeding 90%, among others.
III. API 7-1: General Standard for Drillstring Components
API 7-1 (Specification for Rotary Drill Stem Elements) is the general standard for rotary drill stem components, covering drill collars, heavy-weight drill pipes, kellys, and subs.
Division of responsibilities with API 5DP:
API 5DP Specification for Drill Pipe (Body, Connections, and Welds)
API Spec 7-1: Other Drillstring Components (Drill Collars, Heavyweight Drill Pipe, Kelly Stems, etc.)
Classification of heavy drill pipe: Although the term “drill pipe” appears in its name, heavy drill pipe (HWDP) is manufactured to API 7‑1 rather than API 5DP. This distinction should be carefully noted during procurement.
IV. ISO 11961: The International Equivalent Standard to API 5DP
ISO 11961 (Petroleum and natural gas industries — Steel drill pipe) is a drill pipe standard published by the International Organization for Standardization, which is highly consistent with API 5DP in terms of technical content.
The relationship between API 5DP and ISO 11961:
The technical content is broadly equivalent, but API 5DP incorporates additional region-specific requirements, such as API mark certification.
In international procurement, the two are often cited together.
Some items require “compliance with API 5DP or ISO 11961.”
Procurement Recommendation: If your project targets the global market, we recommend prioritizing drill pipes that comply with both API 5DP and ISO 11961.
V. Regional Certification: NS-1 and GOST
In addition to API and ISO standards, different markets also have their own regional certification requirements.
NS-1 (European Market)
NS-1 is a European drill‑tool connection standard, primarily addressing the performance requirements of rotary‑shoulder connections.
Core content:
Performance Evaluation of Joints Under Combined Loading Conditions
Sealing Performance and Torsional Resistance Testing
Drill pipe procurement for the European market
Applicable scenarios: Exports to Europe, or projects in the Middle East, the North Sea, and other regions that adhere to European standards.
GOST (Russian and CIS markets)
GOST (or GOST R) is the national standards system of Russia and the Commonwealth of Independent States. Exporting drill pipes to Russia requires obtaining GOST certification.
Core content:
The product complies with Russian technical regulations.
Factory Quality System Audit
Product Testing and Certificate Issuance
Applicable scenarios: Export to Russia, Kazakhstan, and other CIS countries.
Hebei Longway has obtained GOST RTN certification, enabling its products to enter the Russian market without hindrance.
VI. Certification Systems: API Q1 and ISO 9001
The standard specifies product requirements, while the certification system verifies whether the manufacturer is capable of consistently meeting those requirements.
| Certification | Nature | Function |
| API Q1 | Quality Management System Certification | Prerequisites for API Logo Certification |
| ISO 9001 | International Quality Management System Certification | General Quality Management Capability Certification |
| API logo | Product Certification | Certification of product compliance with API standards |
The logic behind API Monogram certification is as follows: Manufacturers must first obtain API Q1 system certification, and then apply for the API Monogram for specific products. Upon receiving the Monogram, products may bear the “API 5DP” designation along with the API Monogram.
VII. Quick Reference Table for Standards and Certifications
| Standards/Certifications | Scope of Application | Core content | Applicable Markets |
| API 5DP | Drill pipe | Steel grade, size, thread, inspection | Global |
| API 7-1 | Drill string components | Drill collar, HWDP, and square drill pipe | Global |
| ISO 11961 | Drill pipe | Corresponds to API 5DP | Global |
| NS-1 | Rotary table shoulder connection | Connection Performance Evaluation | Europe |
| GOST | Drill rods and components | Russian National Standard | Russia/CIS |
| API Q1 | Quality Management System | System certification | Global |
| ISO 9001 | Quality Management System | System certification | Global |
VIII. Key Points for Standards and Certification Verification in Procurement
When purchasing drill rods, it is recommended to specify the following in the contract:
| Verification item | Requirements |
| Product Standard | Specify API 5DP (including the year of the edition) or ISO 11961. |
| Component Standard | Heavy drill pipes, drill collars, and similar items must be clearly identified as conforming to API 7-1. |
| PSL level | Clearly define PSL-1/2/3 |
| Certification Requirements | Please provide the API logo license number; it can be verified on the official website. |
| Regional Certification | For example, exports to Russia require GOST, while exports to Europe require NS-1. |
| Quality Document | The MTC shall include chemical composition, mechanical properties, and nondestructive testing results. |
| Traceability | The heat number is consistent with the MTC. |
9. Frequently Asked Questions (FAQ)
Q1: What is the difference between API 5DP and ISO 11961?
The technical content is essentially the same; API 5DP adds a requirement for API logo certification, while ISO 11961 is the internationally recognized standard.
Q2: Which standard does the heavy drill pipe comply with?
API 7-1, not API 5DP. Please pay special attention when placing orders.
Q3: Are the API Monogram and API Q1 the same thing?
No. API Q1 is a quality management system certification, while the API Monogram is a product certification. To obtain the Monogram, you must first pass the Q1 certification.
Q4: What certifications are required for exporting to Russia?
GOST certification. Hebei Longway already holds GOST RTN certification.
Q5: How can you verify that a supplier’s API certification is valid?
Please provide the API logo license number, which will be verified through the official API certification inquiry system.
X. Summary
| Key points | Core content |
| Product Standard | API 5DP (drill pipe), API 7-1 (drill string components) |
| International standard | ISO 11961 (corresponding to API 5DP) |
| Regional Certification | NS-1 (Europe), GOST (Russia) |
| System certification | API Q1, ISO 9001 |
| Procurement Verification | Standard version, PSL grade, certification number, MTC, traceability |
Understanding the standards and certification systems for drill pipes is essential to ensuring that compliant products are procured and that market access is smooth. As different markets have varying standard requirements, it is crucial to clarify the certification obligations of the target market prior to procurement, thereby preventing customs clearance delays or project setbacks caused by missing certifications.
Do you need to procure drill pipes for your project that comply with API 5DP, GOST, or NS-1 standards?
Contact Hebei Longway Petroleum Equipment Co., Ltd.
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Hebei Longway holds numerous international certifications, including API 5DP, API 7-1, API Q1, ISO 9001, and GOST, and its products are exported to more than 40 countries worldwide.
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