Everything You Need to Know About Drill Pipes

Welcome to our comprehensive guide on drill pipes. In this article, we will cover everything you need to know about these essential tools in the oil and gas industry. Whether you are a seasoned professional or just starting out, understanding drill pipes is crucial for successful drilling operations.

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Drill pipes are the backbone of any drilling activity, connecting the drilling rig to the drill bit. They are responsible for transferring power, torque, and drilling fluids downhole, enabling the extraction of oil and gas resources. Without drill pipes, drilling operations would not be possible.

In this guide, we will delve into the different types of drill pipes available, their manufacturing process, and the crucial factors to consider when selecting the right drill pipes for your project. We will also discuss the maintenance and inspection procedures to maximize the lifespan and performance of your drill pipes.

Whether you are interested in the technical aspects or want to understand how drill pipes impact drilling efficiency, this guide has got you covered. So, without further ado, let&#;s dive into the world of drill pipes and equip ourselves with the knowledge to excel in the field.

Components of a drill pipe

A drill pipe is a crucial component of the drilling system used in oil and gas exploration, as well as other drilling applications. It is a hollow, thick-walled pipe that connects the drilling rig to the drill bit and allows for the circulation of drilling fluids. The main components of a typical drill pipe include:

1. Pipe Body: The primary section of the drill pipe is the pipe body, which is a long, cylindrical tube made of high-strength steel. This steel is designed to withstand the extreme pressures, stresses, and abrasion encountered during drilling operations. The pipe body is typically seamless and heat-treated for added strength.
2. Tool Joints: Tool joints are the threaded connections located at the ends of the drill pipe. They are designed to provide a secure connection between adjacent pipes and allow for the transmission of torque and axial loads. Tool joints are made from a higher-strength steel than the pipe body to ensure their durability.
3. Upset Ends: The upset ends are the thicker portions of the pipe near the tool joints. They provide additional strength and wear resistance to the connections and are used to make the transition from the thicker tool joints to the thinner pipe body.
4. Threads: Threads on the tool joints are used to connect one drill pipe to another and to other drilling components, such as the drill collars and the bottom hole assembly. These threads are precision-machined to ensure a tight seal and proper engagement.
5. Hardbanding: Drill pipes often have hardbanding applied to the tool joint shoulders and box ends. Hardbanding is a wear-resistant overlay that helps protect the tool joints from abrasion and extend their lifespan.
6. Internal Diameter (ID): The internal diameter of the drill pipe allows for the passage of drilling fluids and the rotation of the drill bit. It is essential for the circulation of drilling fluids, which help cool the bit, remove cuttings, and provide pressure control.
7. External Coating: Drill pipes may have external coatings to provide additional protection against corrosion and wear. Common coatings include phosphate, copper, or epoxy coatings.
8. Identification Marks: Drill pipes are typically marked with identification information, including the manufacturer&#;s name, pipe size, wall thickness, and grade to ensure proper handling and usage.
9. Length: Drill pipes come in various standard lengths, typically ranging from 30 to 32 feet (9 to 10 meters). Longer drill pipes can be used in some specialized drilling applications.
10. API Specifications: Drill pipes are manufactured according to specific API (American Petroleum Institute) specifications, such as API 5DP, which sets standards for drill pipe manufacturing and performance.

These components work together to form a durable and reliable drill pipe that can withstand the challenging conditions encountered during drilling operations, including high pressures, extreme temperatures, and the mechanical forces involved in drilling through rock and soil.

Types of drill pipes

Standard drill pipes are typically classified based on their size, wall thickness, and material grade. The most common types of standard drill pipes include:

1. API Drill Pipe: These are drill pipes that conform to the standards set by the American Petroleum Institute (API), primarily API 5DP. They come in various sizes (diameters) and grades (strength levels) to accommodate different drilling requirements. The most common API grades are E, X, G, and S, with increasing levels of strength and performance.
2. Size Classification: Drill pipes are categorized into different sizes based on their outside diameter (OD). Common sizes include 2-3/8&#;, 2-7/8&#;, 3-1/2&#;, 4&#;, 4-1/2&#;, and 5&#;. The choice of size depends on the drilling equipment and the capacity required for a specific operation.
3. Grade Classification: Drill pipes are also classified into different grades based on their material composition and mechanical properties. The most common grades include:
   • E Grade: These are the most commonly used drill pipes, suitable for standard drilling operations.
   • X Grade: X-grade drill pipes are designed for extreme drilling conditions, offering higher strength and durability.
   • G Grade: G-grade drill pipes are primarily used in horizontal drilling applications, as they provide better torsional strength.
   • S Grade: S-grade drill pipes are used when high-strength pipes are required, especially in challenging drilling environments.
4. Internal Coatings: Depending on the drilling application and the types of formations being drilled, drill pipes may have different internal coatings to enhance performance. For example, some drill pipes may have a phosphatized or copper-coated interior to reduce corrosion and friction.
5. Threaded Connections: Drill pipes have threaded connections at each end to allow for easy assembly and disassembly of the drill string. The type of thread and its dimensions can vary depending on the manufacturer and the specific application.
6. API Thread Profiles: Drill pipes often use API thread profiles, such as API IF (Internal Flush) and API NC (National Coarse), which are standardized for compatibility across the industry.
7. Hardbanding: Some standard drill pipes may have hardbanding applied to the tool joint shoulders and box ends to increase their resistance to wear and abrasion.
8. API Color Codes: Drill pipes may have color-coded bands to indicate their grade and provide quick visual identification.

These different types of standard drill pipes allow drilling operators to select the appropriate combination of size, grade, and features to match the specific requirements of their drilling project, taking into account factors such as the depth of the well, the geological conditions, and the drilling equipment being used.

Drill pipe specifications and sizes

Standard drill pipe sizes typically refer to the outside diameter (OD) of the drill pipe. These sizes are commonly used in the oil and gas industry and are specified in inches. The most common standard drill pipe sizes include:

1. 2-3/8&#; Drill Pipe: This size of drill pipe has an outside diameter of approximately 2.375 inches (60.3 millimeters). It is commonly used in smaller drilling applications, such as shallow oil and gas wells and water well drilling.
2. 2-7/8&#; Drill Pipe: Drill pipes with an outside diameter of approximately 2.875 inches (73.0 millimeters) are widely used in both oil and gas drilling operations. They are versatile and suitable for various drilling depths and conditions.
3. 3-1/2&#; Drill Pipe: Drill pipes with an outside diameter of approximately 3.5 inches (88.9 millimeters) are also commonly used in the oil and gas industry. They provide increased strength and capacity compared to smaller sizes, making them suitable for deeper drilling applications.
4. 4&#; Drill Pipe: Drill pipes with an outside diameter of approximately 4 inches (101.6 millimeters) are larger and used in heavy-duty drilling operations, such as deep oil and gas wells and geothermal drilling.
5. 4-1/2&#; Drill Pipe: Drill pipes with an outside diameter of approximately 4.5 inches (114.3 millimeters) are among the larger sizes and are used in demanding drilling environments, including deepwater drilling and directional drilling.
6. 5&#; Drill Pipe: This size of drill pipe has an outside diameter of approximately 5 inches (127.0 millimeters). It is often used in high-stress drilling operations and is suitable for deep oil and gas wells.

Please note that while these sizes are commonly used, drill pipes can come in various other sizes and configurations to meet specific drilling requirements. Additionally, drill pipe sizes are specified based on their outside diameter, and the wall thickness can vary depending on the grade and application. The choice of drill pipe size depends on factors such as the depth of the well, the drilling equipment used, and the geological conditions encountered during the drilling operation.

Drill pipe materials and manufacturing process

Drill pipes are critical components in the drilling industry, designed to transmit torque, axial load, and drilling fluids while withstanding the harsh conditions encountered during drilling operations. They are typically made from high-strength steel alloys to ensure durability and performance. The materials used and the manufacturing process of drill pipes are as follows:

Materials for Drill Pipes:

1. Steel Alloys: Drill pipes are primarily made from various high-strength steel alloys. The choice of steel alloy depends on the specific drilling application and the desired mechanical properties. Common steel grades used for drill pipes include:
   • API E Grade: General-purpose steel for standard drilling operations.
   • API X Grade: High-strength steel for extreme drilling conditions.
   • API G Grade: Steel with improved torsional strength, often used in horizontal drilling.
   • API S Grade: High-strength steel suitable for demanding drilling environments.
2. Non-Magnetic Alloys: In some cases, non-magnetic drill pipes are used to prevent interference with magnetic surveying tools. These non-magnetic alloys are typically stainless steels or special alloys designed to be non-magnetic.

Manufacturing Process for Drill Pipes:

The manufacturing process for drill pipes involves several stages to ensure the quality, strength, and reliability of the final product. The process typically includes the following steps:

1. Steel Selection: High-quality steel alloys are chosen based on the desired grade and mechanical properties for the drill pipes.
2. Pipe Production: The selected steel is formed into cylindrical pipes through a hot-rolling process, which involves heating the steel to a high temperature and passing it through rolling mills to achieve the desired diameter and wall thickness.
3. Heat Treatment: The pipes undergo a heat treatment process to enhance their mechanical properties. This typically includes quenching and tempering to improve hardness, strength, and toughness.
4. Upsetting: Upsetting is the process of thickening the ends of the pipe to create tool joints. These tool joints provide a robust connection point for attaching multiple drill pipes together. The ends are often threaded during this process.
5. Thread Machining: The tool joint threads are machined to precision standards to ensure secure and leak-free connections between drill pipes. API standardized thread profiles, such as API IF (Internal Flush) and API NC (National Coarse), are commonly used.
6. Hardbanding: In some cases, hardbanding is applied to the tool joint shoulders and box ends to increase resistance to wear and abrasion during drilling.
7. Quality Control: Rigorous quality control measures are taken throughout the manufacturing process to inspect the dimensions, mechanical properties, and integrity of the drill pipes. Non-destructive testing methods, such as ultrasonic testing and magnetic particle testing, are often used.
8. Marking and Identification: Drill pipes are marked with identification information, including the manufacturer&#;s name, size, grade, and other relevant details.
9. API Certification: Manufacturers that meet API standards must pass a certification process and may apply the API monogram to their products as a mark of compliance.

The manufacturing process for drill pipes is highly regulated to ensure the safety and reliability of drilling operations. Quality control, material selection, and adherence to industry standards are essential aspects of producing high-performance drill pipes capable of withstanding the challenging conditions encountered in drilling wells.

Drill pipe inspection and maintenance

The inspection and maintenance of drill pipes are crucial for ensuring their safety, reliability, and performance during drilling operations. Regular inspections and appropriate maintenance practices help identify potential issues early and extend the lifespan of the drill pipes. Below are standard procedures for inspecting and maintaining drill pipes:

1. Visual Inspection:

• Conduct a visual inspection of the drill pipes before and after each use to check for visible damage, including dents, cracks, and wear.
• Look for signs of corrosion, rust, or pitting on the external surface of the pipes.
• Check the threads for signs of damage, galling, or excessive wear.

2. Non-Destructive Testing (NDT):

• Periodically perform non-destructive testing, such as ultrasonic testing (UT) and magnetic particle testing (MT), to detect internal and surface defects that may not be visible.
• UT can identify issues like internal cracks and wall thickness variations.
• MT is effective at detecting surface cracks and discontinuities.

3. Thread Inspection:

• Inspect the threads of the drill pipes and the tool joints carefully.
• Ensure that the threads are clean and free from debris.
• Check for thread galling, which can lead to poor connections and potential thread failure.

4. Hardbanding Inspection:

• If the drill pipes have hardbanding applied to the tool joint shoulders and box ends, inspect the hardbanding for wear and damage.
• Replace hardbanding if it becomes excessively worn or damaged.

5. Measurement and Calibration:

• Periodically measure and calibrate the drill pipe dimensions, including the OD, ID, and wall thickness, to ensure they are within acceptable tolerances.

6. Cleaning:

• Clean drill pipes thoroughly after each use to remove drilling mud, debris, and contaminants that can lead to corrosion.
• Ensure that the interior of the pipes is free from residual drilling fluids.

7. Preservation:

• Apply a protective coating, such as a rust inhibitor or oil, to the exterior surface of the drill pipes when they are not in use or during storage to prevent corrosion.

8. Lubrication:

• Lubricate the threads and tool joint connections with a suitable thread compound to reduce friction and prevent galling during assembly and disassembly.

9. Storage:

• Store drill pipes in a dry, well-ventilated area away from moisture and corrosive substances.
• Properly secure and support the pipes to prevent deformation or damage.

10. Record Keeping:

• Maintain detailed records of inspections, maintenance, and any repairs or replacements performed on the drill pipes.
• Track the service history of each drill pipe to monitor its condition over time.

11. Repair and Replacement:

• Promptly repair or replace any drill pipes that exhibit significant damage, defects, or wear that could compromise their structural integrity.

12. Certification:

• Ensure that the drill pipes are certified to meet industry standards, such as API 5DP, and that the certification is up to date.

13. Training:

• Train personnel involved in handling, inspecting, and maintaining drill pipes to ensure they are knowledgeable and skilled in proper procedures.

Regular inspections and maintenance are essential to prevent equipment failures and downtime during drilling operations. Adhering to industry best practices and standards is crucial for the safe and efficient use of drill pipes in oil and gas exploration and other drilling applications.

Drill pipe connections and thread types

Standard drill pipe connections and thread types are essential for ensuring a secure and leak-free connection between individual drill pipe sections and other components of the drilling assembly. The American Petroleum Institute (API) has established standardized thread profiles and connections that are widely used in the industry. Here are some common standard drill pipe connections and thread types:

1. API Internal Flush (IF):

• The API Internal Flush (IF) connection is a widely used type of threaded connection for drill pipes.
• It features a flush joint profile, meaning that the threads are set back from the pipe&#;s outer diameter, resulting in a smooth, uninterrupted surface.
• The API IF connection is designed for easy make-up (assembly) and break-out (disassembly), reducing the risk of thread damage during these operations.

2. API Regular Rotary Shouldered (NC):

• The API Regular Rotary Shouldered (NC) connection is another widely used thread type for drill pipes.
• It has a more pronounced shoulder profile than the API IF connection.
• The API NC connection is known for its durability and ability to withstand high torque and axial loads.

3. API Internal Upset (IU):

• The API Internal Upset (IU) connection features an internal upset that thickens the pipe&#;s wall at the joint.
• This connection provides additional strength and is suitable for demanding drilling applications.

4. API Modified Internal Upset (MIU):

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• The API Modified Internal Upset (MIU) connection is an improved version of the IU connection.
• It offers enhanced strength and performance characteristics, making it suitable for challenging drilling conditions.

5. API Full Hole (FH):

• The API Full Hole (FH) connection is designed to provide an uninterrupted inner bore, which helps maintain optimal flow rates for drilling fluids.
• It is well-suited for situations where maximizing the internal diameter of the drill pipe is essential.

6. API Double Shoulder (DS):

• The API Double Shoulder (DS) connection features a double shoulder design for added strength and durability.
• It is used in heavy-duty drilling applications and can withstand high levels of torque and axial load.

These standardized drill pipe connections and thread types are essential for ensuring compatibility and reliability during drilling operations. When assembling a drill string, it&#;s crucial to match the thread types of the drill pipes, tool joints, and other components to ensure a proper fit and prevent leaks or thread damage. Additionally, the use of thread compounds and proper makeup torque is essential to achieve a secure and leak-free connection.

Drill pipe handling and safety precautions

Handling drill pipes involves various safety precautions to protect personnel and equipment during drilling operations. Proper handling practices are critical to preventing accidents, injuries, and damage to drill pipes. Here are some important drill pipe handling and safety precautions:

1. Training:

• Ensure that all personnel involved in drill pipe handling are adequately trained and qualified for their tasks.
• Provide training on safe handling procedures, including the use of lifting equipment, personal protective equipment (PPE), and proper body mechanics.

2. Personal Protective Equipment (PPE):

• Require workers to wear appropriate PPE, including steel-toed boots, gloves, hard hats, safety glasses or goggles, and hearing protection as needed.
• Consider additional PPE, such as fall protection equipment, when working at heights.

3. Lifting Equipment:

• Use appropriate lifting equipment, such as forklifts, cranes, hoists, and tongs, to move and transport drill pipes safely.
• Inspect lifting equipment regularly to ensure it is in good working condition.
• Ensure that equipment operators are trained and certified to operate the machinery safely.

4. Weight Limits:

• Be aware of the weight limits for the lifting equipment and rig floor components, such as elevators and slips, to prevent overloading.
• Use load rating charts and labels to determine the safe working load of equipment.

5. Proper Body Mechanics:

• Train workers on proper lifting techniques to minimize the risk of back injuries and strains.
• Encourage team lifting for heavy drill pipe sections and components.

6. Slips and Elevators:

• When using slips and elevators to handle drill pipes, ensure that they are in good condition and properly adjusted.
• Monitor and maintain the teeth on slips to prevent pipe slippage.

7. Secure Stacking:

• When stacking or storing drill pipes, use suitable pipe racks or storage bins to prevent pipes from rolling or falling.
• Securely anchor stacked pipes to prevent movement.

8. Inspection:

• Regularly inspect drill pipes for damage, wear, and corrosion. Any damaged or compromised pipes should be taken out of service.
• Pay attention to threads and connections for signs of wear or damage.

9. Thread Protection:

• Use thread protectors or caps to cover threads on unused drill pipes to prevent damage and contamination.
• Remove protectors only when pipes are ready for use.

10. Rig Floor Safety:

• Maintain a clean and clutter-free rig floor to prevent tripping hazards.
• Clearly mark and communicate safe zones and restricted areas on the rig floor.

11. Communication:

• Ensure clear and effective communication among rig personnel during drill pipe handling operations.
• Establish hand signals and verbal commands for safe coordination.

12. Emergency Response:

• Have well-defined emergency response procedures in place in case of accidents or incidents involving drill pipes.
• Provide training on emergency response procedures to all personnel.

13. Environmental Considerations:

• Be aware of environmental conditions, such as rain or icy surfaces, that can affect the safety of drill pipe handling operations.

14. Compliance:

• Follow all relevant safety regulations and industry standards, including those established by the Occupational Safety and Health Administration (OSHA) and the American Petroleum Institute (API).

Proper drill pipe handling and safety procedures are essential to prevent accidents and protect personnel, equipment, and the environment during drilling operations. Regular safety training and a strong safety culture within the drilling team are key to ensuring safe drill pipe handling practices.

Drill pipe selection for different drilling applications

Selecting the appropriate drill pipe for different drilling applications is essential to ensure safety, efficiency, and the successful completion of drilling operations. The choice of drill pipe depends on several factors, including the drilling environment, well type, formation characteristics, and equipment used. Here are some considerations for drill pipe selection in various drilling applications:

1. Standard Drilling Applications:

• For standard vertical drilling applications in relatively soft or moderately hard formations, standard drill pipes made of API E-grade steel are often sufficient.
• Common drill pipe sizes like 2-7/8&#; or 3-1/2&#; with API Regular Rotary Shouldered (NC) or API Internal Flush (IF) connections are frequently used.

2. Directional Drilling:

• In directional drilling, where the drill bit is steered to create a non-vertical wellbore, higher-strength drill pipes may be required. API G-grade or API S-grade drill pipes are commonly used due to their improved torsional strength and durability.
• Drill pipes with modified internal upsets (MIU) or double shoulder (DS) connections can withstand the increased stresses associated with directional drilling.

3. Horizontal Drilling:

• Horizontal drilling typically involves drilling a horizontal wellbore from a vertical or deviated starting point. Drill pipes with high torsional strength and resistance to buckling are essential.
• Drill pipes with API G-grade or API S-grade and double shoulder (DS) connections are often used for horizontal drilling.
• Specialized spiral drill collars may be incorporated into the drill string to reduce friction and increase stability.

4. Deepwater Drilling:

• Deepwater drilling in offshore environments requires drill pipes that can withstand extreme pressures, depths, and challenging conditions.
• High-strength steel alloys such as API X-grade are commonly used for deepwater applications.
• Consider using drill pipe sizes of 4-1/2&#; or larger to handle the increased loads, and ensure the connections are rated for high torque and pressure.

5. Casing Drilling:

• Casing drilling involves drilling with the casing in place, and the selection of drill pipes depends on the size and type of casing being used.
• Specialty drill pipes designed for casing drilling applications are available with modified connections that match the casing threads.

6. Geothermal Drilling:

• Geothermal drilling often involves drilling through hard, abrasive formations and high-temperature environments.
• Drill pipes made of high-strength alloys like API X-grade or proprietary alloys may be used.
• Drill pipe connections should be suitable for the high-temperature conditions.

7. Well Intervention and Workover:

• Coiled tubing, rather than traditional drill pipe, is commonly used for well intervention and workover operations. Coiled tubing is a continuous, flexible pipe wound on a reel.
• The choice of coiled tubing size and material depends on the specific intervention requirements and the well&#;s characteristics.

8. Coring:

• When coring to obtain geological samples, specialized core barrels and core drill pipes are used. These are designed to capture and retrieve core samples intact.

9. Underreaming:

• In underreaming operations, where the hole diameter needs to be enlarged, specialized underreamer drill pipes with adjustable cutting tools are employed.

It&#;s crucial to consult with drilling engineers and experts who have knowledge of the specific drilling environment and conditions to select the most appropriate drill pipe for a given application. Additionally, always adhere to industry standards and best practices when selecting and using drill pipes to ensure safety and operational success.

Conclusion: Importance of choosing the right drill pipe for efficient drilling operations

Choosing the right drill pipe for efficient drilling operations is of paramount importance in the oil and gas industry and other drilling applications. The selection of drill pipes has a direct impact on the safety, effectiveness, and success of drilling operations. Here are some key points highlighting the importance of this selection:

1. Safety: Selecting the appropriate drill pipe is crucial for the safety of personnel and equipment. Using drill pipes with the right strength, durability, and connection types minimizes the risk of accidents, pipe failures, and injuries during drilling operations.
2. Efficiency: The right drill pipe enhances drilling efficiency by ensuring that the drilling equipment operates at its optimal performance. Drill pipes with the correct strength and weight characteristics can improve drilling rates and reduce downtime.
3. Wellbore Integrity: Proper drill pipe selection helps maintain wellbore integrity. Using drill pipes that can withstand the drilling environment and formation conditions prevents issues like stuck pipe, wellbore collapse, and lost circulation, which can lead to costly delays and problems.
4. Environmental Impact: Choosing the right drill pipe can also have positive environmental implications. Efficient drilling operations reduce the overall environmental impact by minimizing the time and resources required for drilling, which can include fuel consumption and emissions.
5. Cost-Effectiveness: Drill pipes are a significant investment, and choosing the wrong ones can result in higher operating costs due to frequent replacements, repairs, and inefficiencies. Properly selected drill pipes can lead to long-term cost savings.
6. Operational Success: The success of drilling projects, whether for oil and gas exploration, geothermal drilling, or other purposes, hinges on the ability to reach the target depth, maintain wellbore stability, and recover valuable resources. The right drill pipes play a crucial role in achieving these goals.
7. Adaptability: Different drilling applications, environments, and formations require specific characteristics in drill pipes. Choosing drill pipes that are tailored to the specific needs of each operation ensures adaptability and versatility in drilling projects.
8. Compliance: Meeting industry standards and regulations is essential. Choosing drill pipes that conform to recognized standards, such as those set by the American Petroleum Institute (API), helps ensure compliance and quality control.

In conclusion, the selection of the right drill pipe is not a one-size-fits-all decision. It requires careful consideration of factors like drilling environment, formation type, equipment compatibility, and safety concerns. By making informed choices and following industry best practices, drilling operators can maximize efficiency, reduce risks, and achieve the desired results in drilling operations.

You will only find flush threaded PVC at wholesalers that cater to the drilling contractor. This is NOT what you want anyways. This product is much more expensive than regular PVC pipe. Each piece has to be chucked in a lathe and the male and female threads are machined in each end.

It used to be very common when using PVC pipe for with casing or liner to use regular bell end glue joint pipe. We would additionally add sheet metal screws to each joint to help hold it together as we glued it together and lowered it into the hole. There been more than once that I've been lowering a PVC liner into the well and heard a "whoooosh" as a glue joint pulled apart from the weight of the pipe. Usually about 200 ft down the hole.

Nowadays we normally use Certalock PVC pipe. It is bell and socket, but you don't glue it. It has an o-ring for sealing. Then both the male and female ends have a groove machined in them. There is a hole on the outside of the bell end that you inset a "spline" of PVC to lock the joint together. You will also only find this pipe at wholesale distributors for drilling contractors.

You need to check your states well drilling regulations whether PVC is permissible for casing and under what situations. If it is allowed the regulations will also state the minimum SDR ratio or pressure rating of the pipe. I really prefer 4 1/2" ID PVC instead of 4" PVC, which has an OD of 4 1/2". They Make this casing clear up to a 17.3" OD. It has a wall thickness of over an inch. It's being used instead of 16" steel in California. Not because it's cheaper, it's not. It's being used because it doesn't rust.

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