Walk-in tunnel farming is becoming an important protected cultivation method in Pakistan, particularly for farmers growing high-value vegetables such as tomatoes, cucumbers, capsicum, green chilies, bitter gourd, and squash.

A properly designed walk-in tunnel farming structure can improve crop protection, support off-season vegetable production, and provide a more manageable growing environment.

However, choosing the right galvanized iron (GI) pipes, tunnel dimensions, arch spacing, plastic sheets, and supporting materials is essential for building a reliable and economical structure.

If you are searching for walk in tunnel pipe Pakistan, walking tunnel 16 gauge pipe, galvanized tunnel pipe, or walk in tunnel material cost, this guide explains the important technical specifications, pipe requirements, material calculations, and installation considerations.

1. What Is a Walk-in Tunnel Farming Structure?

A walk-in tunnel is a protective agricultural structure made with curved galvanized steel pipes and covered with agricultural plastic film.

Unlike low tunnels, walk-in tunnels provide sufficient internal space for farmers to enter and perform activities such as irrigation, spraying, pruning, crop inspection, and harvesting.

Walk-in tunnels are commonly used for:

  • Tomato farming

  • Cucumber cultivation

  • Capsicum and bell pepper production

  • Green chili farming

  • Bitter gourd cultivation

  • Squash and other high-value vegetables

A complete walk-in tunnel structure generally consists of galvanized GI pipe arches, supporting wires, ground anchors, plastic covering, ventilation arrangements, and optional drip irrigation and insect netting.

2. Walk-in Tunnel GI Pipe Size and Specifications

Choosing the correct pipe diameter and wall thickness is one of the most important decisions when constructing a walk-in tunnel in Pakistan.

3/4-Inch 16-Gauge GI Pipe Specifications

The following specifications represent a manufacturer-published example of a nominal 3/4-inch galvanized steel pipe.

  • Pipe Type: Galvanized Iron (GI)

  • Nominal Diameter: 3/4 inch

  • Nominal Bore: 20 mm

  • Approximate Outside Diameter: 26.1–26.6 mm

  • Reference Wall Thickness: 1.60 mm

  • Approximate Weight: 0.977 kg per meter

  • Reference Stock Length: 6 meters (approximately 19.7 feet)

  • Application: Suitable structural and agricultural applications subject to appropriate design verification

Actual dimensions, thickness, and weight should always be confirmed against the supplied manufacturer's specification.

What Does 16-Gauge GI Pipe Mean?

The gauge indicates the approximate wall thickness of the steel pipe.

In the referenced manufacturer specification, the 16-gauge pipe has a wall thickness of approximately 1.60 mm.

Pipe strength depends on several factors, including wall thickness, outer diameter, steel grade, bending quality, bracing, anchoring, and local weather conditions.

3/4-Inch vs 1-Inch GI Pipe for Tunnel Farming

Both 3/4-inch and 1-inch GI pipes may be considered for agricultural structures, but they are not automatically interchangeable.

A 3/4-inch pipe is lighter and may be considered for certain compact or lightweight structures if engineering requirements are satisfied.

A 1-inch pipe has a larger diameter and is specified for the main arches in some documented Pakistani walk-in tunnel designs.

For example, a Khyber Pakhtunkhwa Agriculture Department procurement specification uses 1-inch, 16-gauge GI pipes for a walk-in tunnel measuring 12 feet wide and 100 feet long.

Important: Farmers should not replace a specified 1-inch main arch with a 3/4-inch pipe without verifying structural suitability.

3. Standard Walk-in Tunnel Dimensions in Pakistan

Walk-in tunnel dimensions vary depending on crop requirements, available land, weather conditions, and structural specifications.

One documented Pakistani government project provides the following reference dimensions:

  • Tunnel Length: 100 feet

  • Tunnel Width: 12 feet

  • Side Height: 4 feet

  • Maximum Height: 7–7.5 feet

  • Arch Spacing: 9 feet

  • Main Arch Pipe: 1-inch, 16-gauge GI pipe

  • Total Arches: 12

These measurements describe a particular project and should not be treated as universal structural standards.

Farmers planning to use 3/4-inch GI pipes must verify the required pipe length, bending radius, arch spacing, and structural support arrangements separately.

Is a 20-Foot GI Pipe Suitable for a Walk-in Tunnel?

A 20-foot galvanized steel pipe may be considered for certain tunnel designs.

However, the suitability of a particular pipe length depends on:

  • Required tunnel width

  • Required tunnel height

  • Arch bending profile

  • Ground anchoring arrangement

  • Pipe insertion or connection requirements

  • Structural load calculations

A 20-foot pipe should not be assumed to produce a specific 12-foot-wide and 7-foot-high tunnel without checking the complete structural drawing.

4. How Many Walk-in Tunnel Pipes Are Required Per Kanal?

One of the most common questions among Pakistani farmers is:

How many GI pipes are required for one kanal of walk-in tunnel farming?

In Pakistan, one kanal commonly equals 5,445 square feet.

The required number of pipes depends on tunnel length, width, arch spacing, number of parallel tunnels, and additional structural supports.

Basic Pipe Quantity Calculation

The number of arches can be calculated using the following formula:

Number of Arches = Number of Arch Intervals + 1

The number of intervals depends on tunnel length and the selected maximum arch spacing.

For example, a 100-foot tunnel with a maximum spacing of 5 feet requires:

100 ÷ 5 = 20 intervals

20 + 1 = 21 arches

Therefore, 21 main arches would be required for this example.

Example Walk-in Tunnel Material Calculation for 1 Kanal

Consider an illustrative agricultural plot with the following dimensions:

  • Total Area: 5,445 square feet

  • Plot Length: 181.5 feet

  • Plot Width: 30 feet

  • Proposed Tunnel Width: 12 feet

  • Number of Parallel Tunnels: 2

The remaining plot width would be used for access and clearance.

The approximate arch quantities are:

  • 4-Foot Arch Spacing: 47 arches per tunnel; 94 arches for 2 tunnels

  • 5-Foot Arch Spacing: 38 arches per tunnel; 76 arches for 2 tunnels

  • 6-Foot Arch Spacing: 32 arches per tunnel; 64 arches for 2 tunnels

  • 9-Foot Arch Spacing: 22 arches per tunnel; 44 arches for 2 tunnels

These calculations provide estimated main arch quantities only.

They do not include additional pipes required for longitudinal supports, entrance frames, end structures, bracing, or crop-support systems.

Important: These spacing options are mathematical examples, not approved structural recommendations. Final arch spacing must be determined according to the selected pipe diameter, steel specifications, weather conditions, and approved tunnel design.

5. Does the Crop Type Affect Tunnel Pipe Quantity?

Different vegetable crops have different cultivation requirements, particularly regarding crop height, trellising, ventilation, and access.

Capsicum and Bell Pepper

Capsicum cultivation benefits from a structure that allows convenient pruning, inspection, harvesting, and temperature management.

Tunnel height and width should be selected according to the proposed growing system.

Green Chili Farming

Green chili crops require appropriate ventilation, irrigation, and plant spacing.

The main GI pipe structure should be designed according to the tunnel's dimensions and structural loads.

Tomato Farming

Tomatoes may require additional staking, trellising, or plant-support arrangements.

The weight of growing plants and fruits should not be transferred to lightweight tunnel arches unless the structure has been designed to carry those loads.

Cucumber and Bitter Gourd

Climbing crops such as cucumber and bitter gourd commonly require stronger crop-support arrangements and sufficient vertical growing space.

Independent trellising structures may be necessary.

Important: GI pipe quantity should be calculated according to tunnel geometry and structural requirements rather than using a fixed pipe quantity for each crop.

6. Complete Walk-in Tunnel Supporting Materials List

A walk-in tunnel requires several supporting materials in addition to its main GI pipe arches.

Galvanized Iron Pipes

GI pipes form the main tunnel framework. Properly galvanized pipes help resist corrosion and provide a durable structural material when selected and installed correctly.

Galvanized Steel Wire

GI wire may be used for tensioning, supporting the covering system, and other approved structural applications.

Wire gauge and installation methods should follow the tunnel design.

Ground Anchors

Ground anchors help secure the tunnel structure and transfer loads into the ground.

The required anchor size, depth, and arrangement depend on soil conditions and structural loads.

Agricultural Plastic Sheets

Agricultural polyethylene film provides a protective covering over the tunnel.

The selected film should have suitable specifications for greenhouse use, including appropriate thickness, ultraviolet stabilization, and expected service life.

Black Mulching Sheets

Black agricultural mulching film helps suppress weeds, conserve soil moisture, and support crop management.

Polyester Rope and Supporting Accessories

Suitable ropes, clips, fasteners, connectors, and other accessories may be required to secure the covering and supporting components.

Anti-Insect Net

Anti-insect netting can reduce pest entry when ventilation openings and entry points are properly managed.

Drip Irrigation System

Drip irrigation provides controlled water application and can be integrated with fertigation systems where suitable.

7. Example Bill of Materials for a Walk-in Tunnel

The following is a reference material list from a documented Pakistani government walk-in tunnel project.

Reference Tunnel Size: 100 Feet Long × 12 Feet Wide

  • Main Arch Pipes: 12 arches using 1-inch, 16-gauge GI pipe

  • Ground Anchoring Bars: 24 pieces of 3/4-inch MS bar, 2 feet long

  • Wire Stretchers: 2 pieces

  • Galvanized Wire: 6 kg of 12-gauge wire

  • Agricultural Plastic Covering: 20 kg

  • Mulching Sheet: 3 kg

  • Anti-Insect Net: 1 complete set

  • Additional Fittings and Installation Materials: As required

These quantities apply to the referenced government design.

They should not be directly copied for an alternative structure using 3/4-inch GI main arches.

For commercial installation, the complete bill of materials should be prepared after confirming tunnel dimensions, structural design, wind resistance, and installation requirements.

8. Walk-in Tunnel Material Cost in Pakistan

The cost of building a walk-in tunnel in Pakistan varies according to the size and specifications of the structure.

The main factors influencing the total investment include:

  • Galvanized pipe diameter and wall thickness

  • Current market price of GI pipes

  • Tunnel width, height, and total length

  • Number of arches and longitudinal supports

  • Ground anchoring and bracing requirements

  • Plastic sheet thickness and quality

  • GI wire and fitting costs

  • Drip irrigation and insect netting

  • Transportation and installation labor

How to Calculate GI Pipe Cost

The basic pipe cost can be estimated using the following formula:

Total GI Pipe Cost = Total Required Pipe Length × Price Per Foot

For example, if the structure requires 500 feet of GI pipe, multiply 500 by the supplier's quoted price per foot.

Additional materials, bending charges, fittings, transportation, and labor should be calculated separately.

Farmers should request an updated quotation because steel prices and agricultural material costs change over time.

9. Step-by-Step Walk-in Tunnel Installation Guide

Step 1: Select Suitable Agricultural Land

Choose land with adequate sunlight, proper drainage, reliable irrigation water, and convenient access for farming operations.

Step 2: Finalize Tunnel Dimensions

Determine the required length, width, height, structural arch design, pipe specifications, and approved arch spacing.

Step 3: Mark GI Pipe Positions

Measure and mark the positions of the structural arches along both sides of the proposed tunnel.

Ensure proper alignment and consistent spacing.

Step 4: Install Ground Anchors

Fix ground anchors according to the approved design and local soil conditions.

Anchoring is particularly important for tunnel stability during strong winds.

Step 5: Install Galvanized Pipe Arches

Install properly formed GI pipe arches.

Inspect the pipes for excessive flattening, cracks, damaged connections, or significant damage to the galvanized coating.

Step 6: Install Supporting Wires and Bracing

Add longitudinal supports, galvanized wires, connectors, and bracing according to the structural plan.

Step 7: Install Agricultural Plastic Covering

Carefully position the agricultural polyethylene sheet over the tunnel frame.

Secure the covering with appropriate fixing materials, ensuring that sharp pipe edges do not damage the film.

Step 8: Prepare the Irrigation System

Install drip irrigation lines, filters, and other irrigation components according to the crop's requirements.

Step 9: Install Ventilation and Insect Protection

Provide suitable ventilation openings and insect netting where required.

Step 10: Inspect the Complete Structure

Before cultivation, inspect all arches, anchors, supporting components, plastic covering, entry points, and irrigation connections.

10. Difference Between Walk-in Tunnel and Low Tunnel Farming

Walk-in tunnel farming and low tunnel farming are two different protected cultivation methods.

Walk-in Tunnel Farming

A walk-in tunnel provides enough internal height for workers to enter the structure.

It is commonly used for crops requiring regular internal access, plant training, pruning, harvesting, and controlled irrigation.

These structures generally need a more substantial support framework.

Low Tunnel Farming

A low tunnel is a shorter protective structure installed over crop rows or planting beds.

It is commonly used to help protect young plants and support early-season vegetable production.

Low tunnels typically use lighter structural materials than walk-in tunnels, depending on their design.

Main Differences

  • Structure Height: Walk-in tunnels are taller; low tunnels remain closer to the ground.

  • Worker Access: Farmers can enter walk-in tunnels, while low tunnel covers generally need to be lifted for crop access.

  • Structural Materials: Walk-in tunnels generally require more substantial framing and anchorage.

  • Installation Cost: Walk-in tunnels generally require greater initial investment.

  • Crop Management: Walk-in tunnels provide more working space for supported vegetable crops.

Farmers should not confuse low tunnel wire with the structural GI pipes used for walk-in tunnel construction.

For more information, explore Kissan Mall's separate low tunnel farming guide when available.

11. Common Mistakes to Avoid When Purchasing Walk-in Tunnel GI Pipes

Farmers should avoid the following common mistakes:

  1. Choosing a pipe based only on its low price.

  2. Assuming that every 16-gauge pipe has identical wall thickness.

  3. Purchasing pipes before finalizing tunnel dimensions.

  4. Using excessive arch spacing without structural verification.

  5. Ignoring wind bracing and ground anchoring.

  6. Purchasing plastic sheets without checking the required width and thickness.

  7. Using lightweight tunnel arches to support heavy crop loads without an approved design.

  8. Ignoring ventilation and drainage requirements.

  9. Failing to verify pipe bending quality.

  10. Ordering materials without preparing a complete bill of materials.

Proper planning helps reduce construction errors, unnecessary expenditure, and premature structural damage.

12. Frequently Asked Questions About Walk-in Tunnel Farming in Pakistan

Q1. What is the best GI pipe size for walk-in tunnel farming in Pakistan?

The correct pipe size depends on the tunnel dimensions, structural design, location, and expected loads. Some compact designs may consider 3/4-inch GI pipes, while documented Pakistani government specifications use 1-inch, 16-gauge pipes for certain walk-in tunnel arches.

Q2. What is the thickness of a 16-gauge GI pipe?

A manufacturer-published specification for a nominal 3/4-inch GI pipe identifies a wall thickness of approximately 1.60 mm. Always confirm the actual thickness with the supplier.

Q3. Can 3/4-inch GI pipe be used for walk-in tunnel farming?

A 3/4-inch GI pipe may be suitable for certain lightweight or supporting applications. Using it for a main walk-in tunnel arch requires verification of the proposed design and structural loads.

Q4. How many walk-in tunnel pipes are required per kanal?

The quantity depends on the length and number of tunnels, selected arch spacing, and structural design. A calculation based on tunnel dimensions provides a more reliable estimate than a fixed per-kanal quantity.

Q5. What is the standard length of a walk-in tunnel GI pipe?

GI pipes are supplied in different lengths depending on the manufacturer and supplier. A commonly referenced stock length is approximately 6 meters, or 19.7 feet. The actual length required for an arch depends on the tunnel's width, height, and bending profile.

Q6. Which vegetables can be grown in walk-in tunnels?

Common crops include tomatoes, cucumbers, capsicum, green chilies, bitter gourd, and squash. Suitable varieties, planting dates, ventilation, and irrigation practices should be selected according to regional conditions.

Q7. How much does walk-in tunnel farming cost in Pakistan?

The cost varies with tunnel area, steel prices, pipe specifications, support materials, plastic coverings, irrigation arrangements, and labor. An itemized quotation is recommended for an accurate estimate.

Q8. Where can I buy walk-in tunnel pipes in Pakistan?

Kissan Mall provides an online platform for agricultural equipment and farm supply inquiries. Farmers can visit www.kissanmall.pk to explore relevant tunnel farming products and request information on availability and quotations.

13. Buy Walk-in Tunnel GI Pipes and Farming Materials from Kissan Mall

Planning a walk-in tunnel farming project for tomatoes, cucumbers, capsicum, green chilies, bitter gourd, or other vegetables?

Kissan Mall helps farmers source agricultural equipment and tunnel farming materials across Pakistan.

Explore products and supporting materials such as:

  • 3/4-Inch Galvanized GI Pipes

  • Tunnel Supporting Materials

  • Galvanized Wire and Fittings

  • Agricultural Plastic Sheets

  • Black Mulching Sheets

  • Tunnel Installation Accessories

To request a project quotation, provide your land area, tunnel dimensions, crop type, installation location, and preferred material specifications.

Visit Kissan Mall: www.kissanmall.pk

Conclusion

Selecting the correct walk-in tunnel pipe in Pakistan is an essential step in successful protected vegetable cultivation.

The 3/4-inch, 16-gauge GI pipe is a useful agricultural construction material, but its suitability as a main tunnel arch depends on the structural design and expected loads.

Farmers should carefully evaluate the pipe diameter, wall thickness, bending profile, tunnel dimensions, arch spacing, anchoring system, supporting materials, and plastic covering before purchasing construction materials.

Accurate planning helps farmers build more practical and reliable tunnel structures while controlling unnecessary material costs.

Kissan Mall – Your Trusted Online Agricultural Equipment and Farm Supplies Platform in Pakistan.