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M20 Anchor Bolts for Concrete Fixing | Hebei Wotu Fastener Manufacturing Co., Ltd.

M20 anchor bolts for concrete and foundation connections

M20 anchor bolts are used to secure structural steel, equipment bases, frames and other assemblies to concrete or foundations. The key purchase decision is not the M20 thread alone: the anchor type, overall length, embedment, steel grade, corrosion protection and installation method must suit the connection.

Before requesting a quotation from Hebei Wotu Fastener Manufacturing Co., Ltd., identify the application and the design information that controls the connection. Ask which M20 anchor bolt configurations, materials, finishes and documentation can be supplied for your project.

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Match the anchor configuration to the foundation connection

M20 anchor bolt selection

When comparing M20 anchor bolt options, review the anchor shape, total length, thread and projection, anchorage detail, material or strength grade, corrosion protection, nut and washer compatibility, applicable standard and required documentation. The correct choice follows the structural drawing and installation method rather than the thread diameter alone.

Criterion What To Check Why It Matters Buyer Tip
Anchor bolt form and embedment style Confirm whether the job needs cast-in L-type, J-type, straight, headed, or post-installed M20 anchor bolts, and match this to the drawing detail. The bolt form affects pull-out resistance, installation sequence, template setting, and whether the anchor can be placed before or after concrete is poured. Ask: Are these M20 anchors for cast-in concrete, existing concrete, base plates, machinery, or structural steel columns?
Thread length and usable projection Compare the required exposed thread length with the base plate thickness, washer, nut, grout layer, and any leveling allowance. Too little projection can prevent full nut engagement; too much projection can interfere with equipment or require cutting on site. Ask for the required total length, embedment depth, and above-concrete projection instead of ordering by diameter only.
Steel grade and load requirement Match the specified material grade or strength class to the engineering requirement and request the relevant material confirmation if needed. M20 describes diameter only; two M20 anchor bolts can have very different tensile and shear capacity depending on steel grade and manufacturing route. Ask: What grade or standard is shown on the project drawing or bill of materials?
Surface finish for the environment Choose plain, zinc-plated, hot-dip galvanized, or another specified coating based on exposure conditions and drawing requirements. Coating choice affects corrosion resistance, thread fit, nut assembly, and long-term performance in outdoor, wet, or industrial environments. Ask whether the anchors will be used indoors, outdoors, in concrete with moisture exposure, or near corrosive chemicals.
Matching nuts, washers, and templates Verify whether nuts, washers, lock nuts, or positioning templates are included and compatible with M20 threads and coating thickness. Many site delays come from anchors arriving without matching hardware or with thread fit issues after coating. Ask for the thread standard, quantity of nuts and washers per bolt, and whether a placement template is required for bolt spacing.

Key checks before ordering M20 anchor bolts

The main distinction is between cast-in anchor bolts placed before concrete is poured and post-installed anchors fitted after the concrete has cured. Cast-in bolts are normally selected from the foundation or base-plate drawing, while post-installed systems depend on the concrete condition, load direction, edge distances and the approved installation method.

M20 only describes the nominal thread size. It does not define the bolt length, anchorage depth, head or plate arrangement, strength grade, coating or suitability for tension and shear loads. Treating every M20 anchor as interchangeable can lead to poor fit, insufficient engagement or site rework.

Start with the connection type and load path. Confirm whether the bolts will hold down a steel column, machinery base, guardrail, pipe support or another assembly, and provide the relevant drawing or anchor layout. The required projection above the concrete, washer and nut arrangement, thread length and anchorage geometry can change with the base plate and installation sequence.

Choose the anchor form for the construction stage. L-shaped, J-shaped, straight rods with an anchoring plate and other configurations suit different foundation details. A cast-in arrangement may be appropriate for new concrete, while a post-installed mechanical or bonded anchor requires separate checks for the existing concrete and the installation system. Do not replace one type with another only because both use an M20 thread.

Confirm material grade and surface protection against the service environment. Indoor structural work, exposed outdoor steelwork, coastal locations and chemically aggressive areas can require different corrosion-control choices. Check compatibility between the anchor, nuts, washers, base plate and any coating or grouting system; a coated bolt is not automatically suitable for every environment.

For the next step, send the required quantity together with the anchor drawing, bolt length or projection, concrete or foundation details, required material or strength grade, finish and destination. Ask the supplier to confirm the proposed configuration, applicable standard, available inspection or material documents and any details that remain open before approving a bulk order.

Criteria Importance Description Example Options
Anchor type Critical for fit and load transfer Cast-in anchors, bent anchors, straight rods with plates and post-installed systems are not interchangeable just because they share an M20 thread. The selected form must match the construction stage and the foundation detail. A new equipment foundation may use cast-in anchor bolts, while an existing slab may require a separately checked post-installed anchor system.
Length, embedment and projection High impact on installation success The bolt must provide the required anchorage in concrete while leaving enough exposed thread for the base plate, washer, nut and any leveling or grouting arrangement. Too little projection can prevent tightening; too much may interfere with equipment or covers. A base plate with grout below it may need a different exposed thread length than a plate seated directly on concrete.
Material or strength grade Controls mechanical suitability The grade should follow the structural design or project specification. A higher-strength bolt is not automatically the right choice if the concrete, nut grade, washer type or installation detail has not been checked as a system. For a column base, the specified bolt grade should be compared with the drawing and matching nut and washer requirements.
Surface protection Important for service life and assembly compatibility The finish should suit the exposure environment and remain compatible with mating components. Coatings can affect thread fit, nut selection and corrosion behavior when different metals or treatments are combined. An exposed outdoor frame may need a different finish than an indoor machinery base in a dry workshop.
Documentation and approval basis Important for bulk orders and project acceptance Before ordering, confirm which standard, drawing, inspection record or material document is required. This avoids disputes where the supplied anchor has the right thread size but does not match the project approval package. A purchasing team may request material documents and dimensional confirmation before releasing a batch order.

Product Selection

Related Options

For a steel base plate fixed to a concrete foundation, the priority is a configuration that matches the hole pattern, required projection and load-transfer detail. Compare options by installation stage, anchorage arrangement and environmental exposure, then confirm the final dimensions and materials against the project drawing instead of assuming that a generic M20 bolt will fit.

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Frequently Asked Questions

Is an M20 thread size enough to specify an anchor bolt?

No. M20 only identifies the nominal thread diameter. You also need to confirm the overall length, thread length, projection above concrete, anchorage shape, material or strength grade, coating, nut and washer arrangement, and the drawing or standard that controls the connection.

Should I choose cast-in or post-installed anchors?

Cast-in anchors are planned into new concrete work and usually follow the foundation or base-plate drawing. Post-installed anchors are used after concrete has cured, but the selection depends on concrete condition, edge distance, hole preparation, load direction and the approved installation method.

Can I replace an L-shaped anchor bolt with a straight anchor rod?

Not without checking the design. Different anchor shapes transfer load into concrete in different ways and may require different embedment, plates, nuts or installation steps. If the drawing specifies one form, confirm any substitution with the project engineer before ordering.

What finish should be considered for outdoor use?

Outdoor anchors usually need corrosion protection that matches the exposure and the connected parts. Hot-dip galvanizing or another suitable surface treatment may be considered, but compatibility with nuts, washers, base plates, grout and any project specification should be confirmed before purchase.

What information should be sent for a quotation?

Send the anchor drawing or a clear sketch, quantity, thread size, total length, thread length, required projection, anchor shape, material or grade, finish, nut and washer requirements, and destination. If any detail is unknown, ask the supplier to identify what must be confirmed before production or bulk supply.

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Please include the application or anchor drawing, required length or projection, and the material, finish or quantity you need so the proposed M20 anchor bolt configuration can be checked.